Inadequate sexual response may be due to a lack of sexual desire (LIBIDO) or to an inadequate performance; or it may be that there is a lack of satisfaction or ORGASM. Lack of sexual desire may be due to any generalised illness or endocrine disorder, or to the taking of drugs that antagonise endocrine function (see ENDOCRINE GLANDS). Disorders of performance in men can occur during arousal, penetration and EJACULATION. In the female, DYSPAREUNIA and VAGINISMUS are the main disorders of performance. DIABETES MELLITUS can cause a neuropathy which results in loss of erection. IMPOTENCE can follow nerve damage from operations on the PROSTATE GLAND and lower bowel, and can be the result of neurological diseases affecting the autonomic system (see NERVOUS SYSTEM). Disorders of satisfaction include, in men, impotence, emission without forceful ejaculation and pleasureless ejaculation. In women such disorders range from the absence of the congestive genital response to absence of orgasm. Erectile dysfunction in men can sometimes be treated with SILDENAFIL CITRATE.

Sexual dysfunction may be due to physical or psychiatric disease, or it may be the result of the administration of drugs. The main group of drugs likely to cause sexual problems are the ANTICONVULSANTS, the ANTIHYPERTENSIVE DRUGS, and drugs such as metoclopramide that induce HYPERPROLACTINAEMIA. The benzodiazepine TRANQUILLISERS can reduce libido and cause failure of erection. Tricyclic ANTIDEPRESSANT DRUGS may cause failure of erection and clomipramine may delay or abolish ejaculation by blockade of alpha-adrenergic receptors. The MONOAMINE OXIDASE INHIBITORS (MAOIS) often inhibit ejaculation. The PHENOTHIAZINES reduce sexual desire and arousal and may cause difficulty in maintaining an erection. The antihypertensive drug, methyldopa, causes impotence in over 20 per cent of patients on large doses. The beta-adrenoceptor-blockers and the DIURETICS can also cause impotence. The main psychiatric causes of sexual dysfunction include stress, depression and guilt.