The emotional causes of retarded ejaculation

When a man is unable to ejaculate and there are no physical problems stopping him, he may be preventing himself, consciously or unconsciously, from ejaculating. This may be hard to believe, but the evidence bears it out. Many emotions, some of which may be so suppressed that a man is unaware of them, can contribute to non-ejaculation. For example, fear of being unable to satisfy a woman can be a big element of the problem. So can fear of not living up to her expectations; fear of coming too quickly; fear that his partner will leave him, and so on. The other big culprit is anger, where ambivalent feelings exist towards a partner in a relationship - for example where both love and hate are components of a couple's feelings for each other.

The strangest aspect of many of these stories is that the men concerned have resorted to faking orgasm to try and get themselves out of their difficulties. In many cases they will wear a condom so that the absence of flowback (seepage of semen from the vagina after intercourse) does not give them away. However it is done, a faked orgasm introduces another destructive element into the problem, and further erodes communication between the two partners about the issue. This is not surprising, because men very often see these issues as something they should solve by themselves.

There are all kinds of male assumptions about masculine strength and weakness here: many men see it as as a failing if their penis will not get hard, thrust away, and ejaculate on demand, and they are not inclined to discuss what they see as their failings with their partner!

So the first part of a cure for non-ejaculation is good communication between the partners. Good communication not just about sexual difficulties, but about emotional issues as well. If a man is having trouble ejaculating because he is angry about his partner's lack of sexual responsiveness, or because he senses her suppressed resentment about sex (being seen as a sex object, perhaps, and not appreciated for herself), or even at his failure to ejaculate, it can be incredibly difficult to approach the issue frankly and openly. Some men simply do not know how to communicate emotional matters, while others have an inbuilt resistance to doing so because they see such discussions as weak or unmanly. Other men may fear hurting their partner by speaking frankly, or may perhaps anticipate her anger if she interprets what is being said as blaming her for the problem. There is no simple route to emotional openness, especially if you have never learnt how to communicate your feelings and thoughts. Counselling may help here, of course. But many men refuse even this option, at least up to the point where the very survival of their relationship may be threatened.

Perhaps the most common psychological reason a man cannot ejaculate when he has sex is that he resents the balance of power or influence around sex in a couple's relationship. Many men and women still cling, maybe even unconsciously, onto the belief that the man must lead the way in sex, or that a woman is less sexually responsive than a man, and that her orgasm and sexual pleasure are something that he must "give her" - and, by implication, therefore, that if he cannot give her an orgasm, or even sexual pleasure or satisfaction, then he has failed as a lover, and perhaps as a man. There is also a great deal of pressure on men to see themselves as sex machines, with a hard penis ready in an instant to make love.....but the truth, of course, is that male sexual desire can be as delicate as female sexual desire. But unless a man is emotionally mature and the couple are in a loving, trusting relationship, he may find it difficult to express his self-doubts and feelings. And this all assumes that there is no unexpressed resentment or anger eating away at the relationship, which unfortunately is rarely so in cases of non-ejaculation.

Such anger can take many forms, and can have many causes. In one case, a man who could not ejaculate was angry at his partner because she was more successful in her career than he was in his. She spent a lot of time away from him, and he complained that the only time they had together was when they were making love. It seemed almost as though his non-ejaculation was an attempt to hold onto her for longer...or maybe a way of punishing her for not spending more time with him? In many many cases, couples with difficulties of orgasm are angry, resentful, ambivalent or have some other underlying emotions affecting their relationship.

Inability to ejaculate with a partner - "partner anorgasmia"

When a man cannot come during intercourse, it may be a problem with every woman he has sex with, or only with one particular partner. The latter condition is called "partner-specific anorgasmia". Men who experience anorgasmia or retarded ejaculation admit to feeling hostile or turned off by their female partners, yet they have astoundingly long lasting penile erections, and they can often have intercourse vigorous and long lasting enough for the women to experience multiple orgasms. If the problem is partner-specific, and a man can have normal intercourse with another partner, then the cause of the ejaculatory difficulty would seem to be a relationship issue. By contrast, if the man can ejaculate through masturbation yet cannot have have an orgasm with any woman he has sex with then the problem lies in his attitude to sex and women.

Partner-specific anorgasmia is sometimes a sign that a man either dislikes, or resents, or feels hostile towards, or has emotionally rejected his partner, or that he does not wish to impregnate her, or that he wishes to deny her the pleasure of seeing him achieve orgasm through intercourse.

A man in this position often seems compelled to try and satisfy his partner, even when he doesn't experience her presence or touch as sexy or stimulating. He works hard to give his partner an orgasm, yet his own pleasure is low on his list of priorities. This means there is a lot of hidden anger and a lot of guilt floating around somewhere in the relationship. Such men may even act as though their orgasm was designed to satisfy the woman's needs and desires rather than their own.

These men can get an erect penis even when their level of desire for their partner is very low: so low, perhaps, that other men's penises would not even stir in the same situation. But they often feel their penis to be "numb" or insensitive, incapable of producing the gradually increasing arousal and sensation necessary to stimulate arousal and orgasm. In other words, they are not turned on, and their desire is low. However, when masturbating, these men may find their penis is sensitive and they enjoy the sensations of touching it themselves. They enjoy the ever-increasing sensitivity and arousal that leads to orgasm and ejaculation.

Autosexuality

One of the strange things about partner specific anorgasmia or retarded ejaculation is that the man concerned can masturbate to orgasm successfully. In fact, many of these men admit that they really prefer masturbation by their own hand to intercourse. (There may be many more men like this who avoid sexual partners altogether and are therefore never identified as anorgasmic during intercourse.)

Perhaps this is because only when free of the compelling need to satisfy his partner, can a man like this enjoy his own touch, his own sexuality, and his own orgasm. About 35% of men who are treated for retarded ejaculation will say that they like their own touch on their penis better than that of a partner because "after all, who would understand it better than me...I've been doing it all my life!"  Men who think like this may also feel guilty that they actually may prefer their own stimulation to being with a partner, and so they lock themselves into a cycle of ever more desperately wanting to please their partner but resenting the feeling that they "have" to do so.

The "usual" treatment method 

The goal of the "normal", by which I mean "traditional", therapy for this problem is a form of progressive desensitization. To cut a long story short, this involves him masturbating to orgasm many times, but each time he does so, his wife or partner is more closely involved in the process, until eventually he is able to put his penis inside her and ejaculate in her vagina.

The crucial aspect of this treatment, on which it relies for its success, is the intensity of the level of stimulation of the man by his partner, and his ability to switch off his critical faculties and lose himself in his sexual fantasy. The more stimulation, the better, is how the logic goes, so often the suggestion is made that the man uses porn to increase his arousal, or has his female partner dressing up or using sex toys or talking dirty or whatever turns the guy on. It will not, however, have escaped your notice that this method make no mention of the need to resolve the relationship issues that may lie at the root of the sexual problems.

[Another variation of retarded ejaculation - emission but no ejaculation

In some cases - a very few cases - a man will achieve an erect penis, be able to enjoy intercourse, and feel himself enter the emission stage of ejaculation - the part where semen is expelled into the upper passages of the penis - but fail to achieve the powerful expulsion phase of ejaculation, which is the part of the ejaculatory response where powerful contractions of the muscles around the penis expel the seminal fluid with the accompanying sensations of physical pleasure and emotional release. According to sexual therapist Helen Kaplan, men with this challenge are often over-critical of themselves, and concerned about their performance. Treatment has been the same as for retarded ejaculation - as described above.]

The conventional treatment outlined above for retarded ejaculation often seems quite cruel - at least to the guy's penis! The manual stimulation that is an essential part of the treatment is often aggressive and forceful, since this roughness may be necessary to stimulate his ejaculatory reflex. And even where the problem only exists with one partner, the man who cannot have orgasm during sex is often seen as being at fault, even though it may well be perfectly reasonable for him not to want sex, or to experience some negative feelings towards his partner. It may, in fact, be relationship therapy that is needed, not sex therapy! It's a strange fact, though, that this treatment does sometimes work: at least, it restores the guy's ability to ejaculate in a vagina.

This treatment has also been criticized because it demands so much of the man - that he almost be made to give up his orgasm - and this from a man who may be having sexual difficulties in the first place because he resents having to give so much to his partner, whose role in the relationship may be passive and unassertive anyway. Many a man like this experiences sex as a continuous demand for performance, but has no way to experience himself as being used. Instead, he has flashes of disgust and/or hatred for his partner. He may also feel disgusted with his own ejaculate, as expressed by a fear of soiling his partner with it. This may be a sign of his turned-off state. People in a sexual situation but not aroused often have disgust reactions that disappear when they are aroused.

(See Principles and Practice of Sex Therapy, ed., Sandra Leiblum, pub., The Guilford Press, 2000.)

Another difficulty is that the rough and intensive masturbation necessary to get the man to the point of his orgasm and the insertion of his penis into her vagina are heavy demands to place on the female partner who may be resentful and frustrated about her partner's inability to ejaculate. These demands may be made worse if she knows only too well that the man is simply not aroused by her, a fact that she will sense if it is true. None of this seems like a recipe for a happy resolution of the problems.

A new model of treatment for men with retarded ejaculation

Well, the first thing I think it worth saying is that it is important to accept that your orgasm is for yourself - not for your partner. Yes, it is! For one thing, it is rather difficult to have an orgasm for someone else! Your partner has her own orgasm which she can enjoy, even if she enjoys seeing you have your orgasm. It certainly is not selfish to have an orgasm inside a woman just for your own enjoyment (assuming she is agreeable to the process, of course)!  Nor is it wrong not to want to have an orgasm inside a woman, or not to want a pregnancy.

But these things need to be communicated. Can a man say he resents working hard during sex, or that he resents the demands placed on him? Or a woman find a way to express her disappointment there is so little of the emotional intimacy that would be satisfying to her? It is through communication of this sort that a couple begin to change their behavior and get in touch with their feelings and their more authentic emotional and sexual energy. So, if you find sex tedious, or disgusting, or more like work than pleasure, or that your partner does not turn you on, it may be worth experimenting with saying these things. And the woman must be allowed to express her complaints. She may, for example, not realize that the man resents being the "workhorse" of sex, doing everything, and she is unlikely to want sex in this form to continue once she knows this. 

But even if you are dealing with any build up of unexpressed resentment, anger or lack of communication, how do you go about becoming fully sexual functional again? Now, that is the million dollar question! 

Well, could you make the objective of sex simply to be close, to feel intimate, affectionate and warm towards her? Does that sound like a strange idea?

I ask because this is generally the first step in this kind of sex therapy - to move away from being penis-in-a-vagina and orgasm-centered to being relaxed, comfortable, together in bed and naked,  free of conflict or sexual pressure. This produces a relaxed environment in which the man and his penis do not feel pressured to perform - indeed, it does not matter whether they perform or not, since ejaculation is not the aim of the experience - yet at the same time it gives the woman much of what she really wants. That is emotional closeness, affection and cuddling, affectionate embraces and words, lots of time, appreciation of her beauty and feminine qualities, sensitivity, caring and emotional connection. This is easier than you might think, and there are some great ways of doing it that you will love too.

But what if you're doing this and you get an erect penis and want to put it into her? Would you thrust away for ages and not come, leaving yourself more critical than before, and leaving your partner perhaps blaming herself, or blaming you, or resentful? In reality you can be alongside her and not use your erection. You can stop thinking you have to pleasure her, and become more aware of your own needs and desires, for they are a legitimate part of the sex act too. In essence, this is about relaxation, not performance. Yet I wonder how many guys know what relaxation really is? Certainly a lot of men seem to feel they cannot relax - they are driven to perform, always to be doing. It's the same urge that men put on themselves to perform during sex, including pleasing their partner and having a satisfactory orgasm and ejaculation themselves. 

Relaxation is about suspending pressure - time pressure, pressure to perform, pressure to get things done. It is about being in the here and now, aware of what is happening and going on in the moment of time and space you are occupying: in other words, in the context of this sexual adventure, not concentrating on the end result, but on the process itself. It is also about fun rather than competition, even when the competition is with yourself or, more accurately, your own internal standards. And lastly, it is about losing yourself into what you are doing - being wholly absorbed in the sexual process, not feeling as if you are standing back and watching yourself performing. In other words, relaxation can be seen as about abandoning much of what may serve to give you a sense of identity and place in the world. Can you be abandoned in this way during sex? It may seem very difficult for many men, especially those for who control is an important element of life.

A new way of treatment

The first step is to be committed to learning a different way of being sexual, and to know that your lover or partner is fully supportive in the process. If she is not going to work with you, then you have another issue to deal with, for she must be accepting of the idea that penile-vaginal intercourse may not be a part of your love life for a time while you focus on a different way of being sexual. 

The next step in the process is to understand and accept that your whole body is an erogenous zone. While many men know that a woman wants to be touched sensuously all over, not just on her nipples, breasts and vulva, we are less accustomed to thinking of men as having the capacity to be aroused by touch. This has  a lot to do with the way boys are brought up - that is, they learn that manly touch is a slap on the back, an elbow in the ribs, or a firm handshake. Other touching, they may be taught, is "gay" or "sissy" or "feminine". In reality, touch is the basis of tender loving affection, which we all experience as babies, and which we continue to crave throughout our lives. Without physical touch, we can literally lose touch in an emotional sense with our lovers. Touch is great to both give and receive, and when given without the expectation of sex, can be a tremendously sensual experience in its own right.

Next, stop thinking of sex as a sequence of events - foreplay, penile penetration, intercourse, lying together afterwards. Think rather of  the  pleasure of lovemaking as a whole. Then your model of lovemaking can include talking, massage, fondling, lying side by side holding hands, caressing, kissing, rolling around on top of and underneath each other, licking, sucking, and fondling all the bits of each other's bodies, including the penis and vulva. For example, have you ever experienced the sensuality of a foot massage, or sucked your partner's toes, or licked the area between area between them? No? Then why not give it a try? But remember to do it in a relaxed way! And of course you may begin to see how much fun there is to be had in all aspects of sensual connection when your partner is happy to share in the fun. If she's not supportive, however, lovemaking is constrained, prescribed, and less than it might be. And if your partner is not giving you what you want, perhaps your penis is withholding what you can give her in return? 

You may have learnt a very different style of lovemaking - a few perfunctory gropes and kisses, a bit of licking and nibbling, no holding or cuddling, and then straight into the penis-in-vagina routine. But this will certainly not satisfy most women, and it will not arouse you much either. When you begin this new stuff about being held or cuddled by your lover, engaging in this delicate sensual touch, perhaps thinking it's a waste of time, that you should be getting down to the sexy stuff, you might feel uncomfortable. If you find the idea of being held by your woman difficult, how do you react to the suggestion that you might let your her touch and caress you in this sensual way while you lie back and enjoy it? Yes, that means not being in control! A frightening thought, perhaps. So take it from me, it can be very arousing for a woman to find that her man trusts her enough to lie back and let her touch him gently, sensuously and lovingly. 

All of this reflects the way men are brought up to regard sex: as something that a man has to get off a woman, an achievement that proves his masculinity, perhaps, or as something he has to do to her, rather than with her.

If you think like this, then you might like to try and change your point of view. See cuddling and touching each other as something you are doing for yourself and your own greater sexual enjoyment as well as your partner's.  Remember, the aim of touching and gently caressing is to become relaxed, connected and intimate with your lover. Why does this matter?

I don't know if you have ever experienced that strange sense of being detached from what you are doing, or just plain bored, during sex? This is the kind of feeling that makes sex unsatisfactory, makes a hard penis turn soft, and causes ejaculations to stop happening. And generally it means that you are uncomfortable with the process, or unhappy not being in control, or uncomfortable with physical or emotional intimacy. (Maybe even that you would rather be somewhere else, doing something else, with someone else. If that is the case, then the relationship may be doomed anyway.)

Women are quick to sense when their partner is bored with sensual play, and they may feel turned off by the discovery - why should they give themselves to someone who is detached from what they see as an essential part of the process of lovemaking? So try, no matter how difficult it may be, to engage fully in the process, and also tell your lover what you are experiencing - even if that means telling her that you find it difficult to relax during sensual play, but that you would like to learn how to do so, and meanwhile you would like to know how best to give her pleasure. 

In short, friendly, relaxed touching is at the heart of a woman's experience of arousal - but what we do not appreciate is that it is essential for most men as well. The simple fact is that men who engage in sensual touching and being touched are often amazed at how quickly their sexual difficulties improve, intimacy is reestablished, and how enjoyable and successful their lovemaking becomes. And, by the way, touching is not something that should be limited to sexual encounters - couples who touch each other regularly in a non-sexual way, with no expectation that sex will follow (apparently men often assume touch equals sex), will have a much better quality of relationship than couples who touch each other only rarely. So why don't you set about finding the most sensitive bits of your partner's body and the way she likes them to be stimulated?

A word about massage

Massage is a great way of offering and receiving loving touch, and even if a man is reluctant to receive it at any length, he can really enjoy the experience of massaging his lover, for it communicates emotions, closeness and caring in a way that men often find difficult to put into words. I recommend these sites as good sources of information. 

Giving and receiving erotic massage

Genital massage for women by men and by women for men

How to ejaculate during sex

So, on to the physical issues. You've established some communication and trust with your lover, maybe you've used sensual massage to become more intimate and connected, and you now want to have intercourse with normal orgasm and ejaculation. 

One indicator of the progress towards genuine sexual arousal that you, as an anorgasmic man, make is the extent to which you experience genuine feeling in your penis. Erections accompanied by erotic feeling are a sure sign of genuine sexual arousal - a product of the freedom to express your sexuality as it really is, rather than as you feel another expects it to be. And the fantasy you experience can also reveal how much you are liberated from the expectation that you will be either  controlling or passive during sex  - as opposed to just being yourself and expressing your own desires and needs.

The key, really, is the first orgasm and ejaculation that is the result of genuine sexual arousal and desire, rather than you feeling obliged to have an orgasm for some reason or other. To achieve such an orgasm you may need to accept that you feel no attraction to your partner, with all the implications that brings with it (like the end of the relationship).

If a relationship is worth keeping, then a good first step is to stop feeling used, and to stop believing that you have to have a reason for sex (like "your partner wants you to satisfy her"). To admit, perhaps, that you want emotional satisfaction, or that you want to be held more than you want sex, is a good next step. And to ask your partner for what you want is even better.

But more than anything, the intellectual and emotional understanding that you need to be aroused before you can really enjoy sexual intercourse is what makes everything slot into place. If you think you are aroused during sex, ask yourself if this experience is similar to the one you have during masturbation - when you are genuinely aroused and orgasm is easy to attain.

If it isn't, then you may not be aroused during sex, and you may need to go over the techniques described above one again to connect with your desires and to become aroused. Patience and assertiveness about your own needs and wants are important here.

Response from a reader with reduced penile sensitivity

An email from a reader: This input is in response to your request for experience or feedback on  a particular problem, that of penile insensitivity. I think it probably affects many more men that we realize, but there is no real information I can find on the Web regarding the physical causes and treatment for low penile sensitivity. I have not "cured" mine, but I have so far been able to optimize what sensitivity I have. Once I recognized my problem for what it was, I made an effort to learn as much as I could about it, and what I can do to improve it. However, I am always looking for  new ideas, types of treatment or drugs that might help - If you have any  ideas, I would very much appreciate hearing them. Anyway, here is my experience with apparently the same problem as your correspondent.

My response was really a reaction to this email which you quote in your web page "Penis, Sex and Masturbation Problems": 

"I am a 23 year old gay male. My partner can have an orgasm very  quickly, but it takes me a long, long time. Also, my penis is not very  sensitive. In fact the only sensitive part seems to be a bit on the underneath of the head. Can I do anything? I am even willing to consider surgery: in fact - I am looking for a cosmetic surgeon now, but with little success. It  makes love-making so very hard! Please help." 

I have had the same problem, life-long. I was always a little slow, and sometimes as a teenager, I would even make my penis sore while masturbating to achieve climax. I thought it was just me, and as long as I was functional, it didn't seem to matter too much. Then after I turned 50,  the problem became so pronounced that I was becoming sexually non-functional. I could get a good erection, but I could not stimulate it enough to achieve orgasm, and eventually the discomfort factor won out, and I would lose my erection. I then decided I would learn more about the problem, and I also finally found an enlightened urologist who helped me experiment with ideas and drugs to alleviate the problem. Now some 12 years later, I am still functional, and even though I still do have less than ideal sensitivity, most of the time I do achieve ejaculation.  

I would estimate my success rate is probably about 90+% for virginal intercourse, 80+% for masturbation, and near 0% for oral sex without some help (which, though is the most erotic feeling kind of sex, just  doesn't have quite a high enough level of stimulation to get me to the  "takeoff" point...I have found that before it goes on too long, if I use some hand masturbation to get me close, I can then enjoy being finished off with oral sex).

What has worked and what has not

Two aspects of my approach have helped significantly:

(1) My urologist informed me that circumcision reduces the sensitivity of the penis. He put me in touch with a group of men who are "restoring" their foreskins through non-surgical methods, using some form of penile skin stretching. Using tape, weights, elastic bands and other methods, you can stretch the "tube" of penile skin over time. It typically takes about 2-3 years to reform a foreskin, some do it in a year, and some like me take longer (I have spent about 7 years off-and-on to gain a fully covering foreskin when flaccid). Restoring the foreskin, of course, doesn't restore all the nerves, blood vessels, sensitive frenulum and inner ridged mucosa with Meissner's corpuscles (the most sensitive parts of the intact  male penis), but it does provide the protection to allow the remaining inner foreskin and glans to de-keratinise and return to a naturally-occurring mucous membrane. This made a significant improvement to my residual sensitivity. See the bottom of this letter for references relating to foreskin restoration. (Or see this page on this website for the account of how this man restored his foreskin.)

What I also found out, is that I was circumcised very tightly, so whatever remaining sensitive inner foreskin of my penis was just below the underside of the glans where the frenulum originally terminated...this is exactly  the comment from your reader who asked the question above. In my case, I was so tightly circumcised that when I had an erection the shaft skin was drum tight. That tended to pull my testicles up into my body during sex to the point of pain. Since restoration, besides better sensitivity, I no longer have the tight shaft skin pulling up my testicles. Another  problem I had, of the annoying sometimes painful rubbing of my bare glans during athletic activity, is also gone forever. Restoration takes some dedication and discipline, but is well worth it. I just wish I could also restore  all those erogenous nerves which were destroyed by circumcision.

(2) I have tried a number of drugs and supplements, but the only one  that made significant improvement in my sensitivity is Yohimbe. I take 4 x 5.4mg tablets per day as a therapeutic treatment, and that makes a very clear difference. I found it took about 3-4 weeks for the sensitivity improvement to be fully realized. I do NOT need to time it before sex. It does have side effects, and my limit of 4 tablets per day is based on the tolerance of the side effects, which are minimal for me at or below that dosage. They include exaggerated urgency in bowel and urination, feeling of shivery cold, slight muscular shaking on occasion, and the feeling of "being wired", like caffeine.  Some have headaches, but that has not bothered me. I have stopped taking Yohimbe for up to a month on several occasions, and after a few weeks I can clearly tell that my sensitivity has diminished. 

Some of the drugs and supplements I tried which have not helped

Testosterone: I tried injections, and found that they would indirectly improve sex by flooding my body with the hormone. Then, a couple of days later, the sensitivity would be gone again. Besides, testosterone is a rather powerful hormone to be taking on a regular basis.

Viagra: Helps to keep an erection a little longer, but doesn't really help the sensitivity.

Dostinex: From what I read, I was sure this would help my sensitivity.  It was reported to speed up recovery times with sensitivity loss after sex. Maybe it gave a little stronger climax when I got there, but it didn't help sensitivity (also called Cabergoline).

Niacin (up to 2g./day):  Made my face flush, maybe provided a little extra erection power, but no better sensitivity.

Arginine: May help to get a little stronger climax when I got there, but no better sensitivity.    

My suggestions to anyone with this problem (you find this a rather common problem with men who are restoring their foreskin):

(1)  Find an enlightened urologist with some experience in sexual problems, who is willing to work with you on the problem, to find unique solutions for an often misdiagnosed problem. It can be physical just as easily as mental.

(2)  Look into non-surgical foreskin restoration to preserve the  little sensitivity still remaining.  As you noted in your comments, do not try surgery...it will almost certainly result in further decreased  sensitivity. See the foreskin restoration page for links.

(3)  Without a doubt, you need the cooperation of your partner to figure out what works.

Physical causes of ejaculatory problems

Diabetes mellitus
Multiple sclerosis
Spinal cord injury
Sympathectomy
Tabes dorsalis
Proctocolectomy
Stroke
Cystectomy
Aortoiliac surgery

Drugs which can interfere with erection or ejaculation

Blood pressure medicine: Beta blockers, Verapamil (Calan), Reserpine (Hydropes), Clonidine (Catapres), Methyldopa (Aldomet)
Diuretics: Thiazides, Spironolactone (Aldactone), Hydralazine
Antidepressants: Prozac, Lithium, MOA's, Tricyclics
Stomach medicine: Tagamet and Zantac, plus other compounds containing Cimetidine and Ranitidine or associated compounds
Anticholesterol drugs
Antipsychotics: Chlorpromazine (Thorazine), Pimozide (Orap), Thiothixine (Navane), Thiordazine (Mellaril), Sulpiride, Haloperidol (haldol), Fluphenazine (Modecate, Prolixin)
Heart medicine: Clofibrate (Atromid), Gemfibrozil, Diagoxin
Hormones: Estrogen, Progesterone, Proscar, Casodex, Eulexin, Corticosteroids
Gonadotropin releasing antagonists: Zoladex and Lupron
Cytotoxic agents: Cyclophosphamide, Methotrexate, Roferon
Non-steroidal anti-inflammatories

Others including Alprazolam, Amoxapine, Chlordiazepoxide, Sertraline, Paroxetine, Clomipramine, Fluvoxamine, Fluoxetine, Imipramine, Doxepine, Desipramine, Clorprothixine, Bethanidine, Naproxen, Nortriptyline, Thioridazine, Tranylcypromine, Venlafaxine, Citalopram

Based on: Beyond Viagra by Alfred  Newman, MD, published by Starhill Press, Alabama, 1999. And Principles and Practice of Sex Therapy by Sandra Lieblum, the Guilford Press, New York, 2000.

Check your medicine packaging to see if it might be the culprit (mind you, it might still be the culprit even if it doesn't say so).

And some others: Alcohol, Amphetamines, Metoclopramide, Opiates, Anticonvulsants, Cocaine...