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Erectile Dysfunction (Syn. ED, Impotence)


There are two types of impotence. Impotentia coeundi (erectile dysfunction) describes the inability to have sex. It is the form that is commonly understood as impotence. The second form, the impotentia generandi (sterility, infertility), stands for the inability to reproduce.

Erectile dysfunction (ED) is a form of impotentia coeundi in which sufficient rigidity (rigidity) of the penis cannot be achieved or maintained for sexual intercourse. The emphasis is on performing sexual intercourse. Masters and Johnson classified a man as impotent in 1970 if he was unable to penetrate in at least 75% of his coital attempts due to a lack of rigidity (stiffness). It can be seen from the above that an ED is not defined by the maximum attainable degree of tumescence (increase in circumference) and / or rigidity. By definition, erectile dysfunction must have been in place for at least six months.

This definition does not make a statement regarding the libido (desire for sex). This has been preserved in the majority of cases. If there is a lack of libido, for example due to a hormonal disorder, an erection cannot be achieved, but the physiological conditions for this are not impaired. ED is not necessarily associated with an ejaculation or orgasm disorder.


In Germany around four to six million men are affected, although exact figures are not available due to the "sensitivity" of the subject. Around two percent of 40-year-old men are affected, and an estimated 25% of 65-year-old men, with a clear age dependency being observed. It should be noted here, however, that the figures are subject to large fluctuations. Unlike in the past, when, in the opinion of the scholars, around 90% of erectile dysfunction were psychologically caused, this is said to be the case today for around a third of those affected. Organic disorders (see below) are assumed to be present in half of the patients affected. The remaining 20% ​​are due to a combination of both causes. Diabetics are affected twice as often. It is important to know that in both sexes, sexual interest and sexual activity do not decrease significantly until they are over 75 years of age. According to research, libido disorders occur in 2% of all men.

Age dependency
Age dependency


In the past, people believed that 80% of ED was psychological, but today multifactorial or organic diseases are assumed to be the main cause. In general, psychoreactive factors predominate in younger patients and organic disorders are more likely to be the causative factors in older men.

General causes

It is well known that the prevalence of erectile dysfunction increases with age (see also). With regard to the pathophysiological causes, there are so far only a number of assumptions, the connection of which has not yet been fully clarified. A structural change in the smooth muscles and tunica albuginea that occurs with age (change in the composition of collagen, reduction in elastic fibers) causes a reduction in the elasticity and compliance of the penis. In addition, there is a reduction in blood flow in old age, including the sensitivity of the erectile tissue to neural, hormonal and pharmacological stimuli.



Smoking increases the risk of cardiovascular diseases and is therefore a secondary risk factor for developing erectile dysfunction. Smoking also increases the risk of erectile dysfunction in patients with cardiovascular diseases, i.e .:
+ in treated heart patients: 56% of smokers vs. 21% of non-smokers
+ in treated hypertensive patients: 20% of smokers vs. 8.5% of non-smokers


Special causes

Changes in the arterial pathway
The mostly arteriosclerotic vascular changes lead to insufficient filling of the erectile tissue, with the entire arterial flow path being affected here as a rule in the sense of arteriosclerosis ("hardening of the arteries"). Risk factors for such vascular changes are lipid metabolism disorders, high blood pressure (arterial hypertension), diabetes (diabetes mellitus) and the aforementioned nicotine abuse. Socialized clinical pictures are:

Coronary artery disease (CHD, narrowing of the coronary arteries)
The severity of CAD seems to correlate with the occurrence and extent of erectile dysfunction.
Peripheral arterial occlusive disease (PAD)
The leg arteries are primarily affected - PAOD, also known as "intermittent claudication", can be noticeable as a shortened walking distance, cold and / or open feet and legs.
Diabetic microangiopathy
In the case of diabetes, in addition to the large vessels, small arteries can also be damaged by remodeling processes.
Coarctation of the aorta, aortic aneurysm
These are changes in the main artery. While coarctation of the aorta is a congenital or acquired narrowing of the aortic arch, aortic aneurysm is a pathological enlargement of the aorta.
Occlusion or reduced perfusion of the internal iliac artery and / or the pudendal artery
These are vessels of the pelvic circulation that supply the penis with oxygen-rich blood in addition to the pelvic viscera.
Occlusion or reduced perfusion of the arteria radicularis magna
This vessel is used to supply the spinal cord with oxygen-rich blood.
Venous and / or cavernous insufficiency, veno-occlusive dysfunction, venous leak
Premature or increased blood outflow leads to insufficient rigidity or the failure of an erection to occur. The cause is remodeling processes of the penile tissue (fibrotic remodeling of the erectile tissue, defect of the erectile tissue [tunica albuginea]); or transmitter disturbances in the erectile tissue. These remodeling processes can not least have been caused by circulatory disorders that have lasted for years. Investigations have shown that the hypoxia-related remodeling processes initially take place in the most peripheral small arteries and initially lead to a partial remodeling of the smooth muscles into fibrotic connective tissue. As a result, a cavernous veno-occlusive dysfunction first develops, without the pathological changes in the penile arteries being detectable in ultrasound examinations. At a later point in time, the penile arteries will also be affected by this remodeling.

Neurogenic causes
This includes all diseases of the central (brain and spinal cord) and peripheral nervous system (nerves). Below are some examples of diseases that can cause erectile dysfunction:

Herniated disc (NPP: nucleus pulposus prolaps)
Diabetic neuropathy
Parkinson's disease (paralysis)
Multiple sclerosis (encephalitis disseminata)
Spinal cord tumor, trauma, compression
Spina bifida
Tabes dorsalis in neurolues
Shy-Drager syndrome
Arnold Chiari Syndrome
Alzheimer's disease
Guillain-Barre Syndrome
Temporal lobe epilepsy
Vitamin B12 Mang

  • Diagnosis

    At this point it should be noted that due to the sensitivity of the subject, many men still keep their problems silent. It is estimated that in more than 70% of cases the diagnosis of erectile dysfunction (ED) is not made in the first place!

    The diagnosis of erectile dysfunction can be divided into three sections:

    Non-invasive diagnostics
    Semi-invasive diagnostics
    Invasive diagnostics
    The individual examinations of the respective diagnostic sections are explained below.

    Non-invasive diagnostics

    Medical history

    The questioning of the patient should cover the entire sexual (dys) function. This can be divided into three sub-areas, which can be disturbed together or individually: sexual desire (libido), erection and ejaculation. The International Index of Erectile Function (IIEF) is helpful for objectifying and monitoring the progress of the complaints. A version of this questionnaire reduced to five questions is the so-called IIEF5, the sensitivity and specificity of which are still 98% and 88%, respectively. The IIEF5 is available as a self-test. Particular attention is paid to the patient's comorbidities (e.g. diabetes mellitus, high blood pressure), risk factors (alcohol, nicotine) and the use of medication; but also the question of partnership problems should not be forgotten.

    The survey should clarify the following points:

    Duration of erectile dysfunction
    How erectile dysfunction started (slowly, suddenly)
    Libido: present, restricted or absent? You can find more information about libido disorders [here]
    Achievable degree of erection according to the Bähre classification:
    E0 No erection

    E1 Low tumescence, no rigidity

    E2 Medium tumescence, no rigidity

    E3 Full tumescence, no rigidity

    E4 Full tumescence, medium rigidity

    E5 Full tumescence, full rigidity

    premature detumescence (relaxation)? You can also read about this [here]
    Can sexual intercourse be practiced?
    Does the penis have a normal shape or are there deviations?
    Erection pain?
    Hardening of the penis?
    Are there morning and / or night spontaneous erections?
    How often, if at all possible, does sexual intercourse take place; how was it before
    Is the ejaculation too early, normal, or too late? You can find information about ejaculation disorders [here]
    # Is there an external disruptive factor that affects the erection (stress, vacation)?
    Does the disorder also exist during masturbation?
    Is the disorder dependent on the partner or sexual practices?
    How high is the patient's suffering?
    Does the patient have an explanation for their erectile dysfunction?
    Ask about accompanying and / or previous illnesses. Compare also [here].
    Ask about past surgeries and / or injuries. Compare also [here].

    Physical examination

    The physical exam usually follows taking a medical history. The examination and assessment of the external genitals (read also: Anatomy and physiology of the male sexual organs) as well as the primary and secondary sexual characteristics have special priority. The following organs and body parts are examined in particular:

    Mammary glands (mammae); Is there possibly a gynecomastia? You can also read about this [here]
    Penis, read also: penis dimensions
    Scrotum, including testicles, epididymis, and spermatic cord
    Assessment of the physique (habitus) hair pattern
    Malformations and / or deformities
    Urethral orifices (hypospadias, epispadias)
    Constriction of the foreskin (phimosis)
    Induratio penis plastica (IPP)
    Neoplasms (benign, malignant)
    Inflammatory changes ([e.g. inflammation of the epididymis [epididymitis]), infection, discharge
    Residues after trauma or operations (e.g. circumcision [circumcision], removal of the testicle because of a testicular tumor [orchiectomy])
    Disease (s) of the testes / epididymis / prostate / seminal vesicle


    The blood and urine tests help to identify diseases that can cause erectile dysfunction. These include, for example, hypogonadism, diabetes mellitus or kidney failure. [Here] you will find normal values ​​(men) for blood count, electrolytes, liver values, kidney values, tumor markers and hormones.

    Blood count
    Cholesterol, triglycerides, blood sugar, possibly HbA1c
    Optional or if an illness is suspected
    Liver and kidney values
    Testosterone in men over 50 years of age or decreased libido or clinical hypogonadism
    Total testosterone and sex hormone binding globulin (SHBG); from this, the free testosterone can be calculated with knowledge of the albumin fraction in the serum
    LH, FSH for low testosterone levels; If necessary, pituitary test (GnRH test)
    Prolactin with reduced libido and / or gynecomastia and / or testosterone <4ng / ml
    Thyroid values ​​(fT3, fT4, TSH)

    Semi-invasive diagnostics

    Ultrasound examination (sonography / duplex sonography), possibly in connection with the SKAT examination

    The simple ultrasound examination allows an assessment of the penis quality. Changes in shape and / or calcifications and / or plaques can thus be diagnosed. The color-coded duplex sonography allows a statement to be made about the arterial blood flow in a side-by-side comparison and in comparison with an extrapenile (i.e. not located in the penis) artery. Further information on duplex sonography can be found [here].

    Neurological and neurophysiological examinations

    Basic neurological examination
    Corpus Cavernosum Electromyogram (CC-EMG)
    Penile Sympathetic Skin Response (PSHA)
    Pelvic floor EMG
    Pudendal nerve latency determination
    Bulbus cavernous reflex
    Recording of nocturnal tumescences (Rigiscan)
    Cavernous injection test (SKIT)

    An erection is usually induced with a PGE1 preparation, for this purpose the substance is injected into the corpus cavernosum (dorsolaterally in the proximal third of the corpus cavernosum)
    a low dosage (5µg or 10µg) should be started and a maximum of one test per day should be carried out
    visual stimulation can improve the success of this test by 70%
    the following information can be derived:
    Success at low dose: Autonomous-neurogenic, psychogenic, or endocrinological cause of ED likely
    Success with high dosage: arterial or cavernous-myocytic degeneration likely
    Success with very high doses: veno-occlusive dysfunction likely

    Invasive diagnostics

    Cavernosography, dynamic infusion cavernosography and -metry

    This is a procedure in which x-rays of the penis and the small pelvis are made after the administration of a contrast medium in order to diagnose structural changes and / or pathologically draining vessels. More information can be found here]
    Example of a venous leak

    Pharmacophalloarteriography (rare)

    before planned vascular reconstructive interventions

  • Therapy

    Causal treatment

    This means recognizing and eliminating the cause of the disease. In the event of a testosterone deficiency (e.g. in hypogonadism), testosterone can be substituted.


    In the meantime there is a whole range of medications, which, however, usually require a prescription and whose use should be carefully considered. A conversation with a trusted doctor is essential here. We strongly advise against taking medication in an uncontrolled manner, for example by ordering via the Internet. There are a number of different classification systems, the following being sorted according to the different modes of action. It should be expressly pointed out once again that information on the active ingredients is given from the literature and does not claim to be complete.

    1. Active ingredients that cause the smooth muscles of the penis to relax

    Nitrite oxide (NO) is catalyzed by the NO synthetase from L-arginine. So far there is only one small study based on the oral application of L-arginine for the treatment of ED. Only weak effectiveness could be demonstrated there. Good results can of course be expected in patients who initially only have low NO levels.

    Phentolamine (Vasomax®)
    This is a non-selective sympatholytic (alpha blocker), which blocks both alpha-1 and alpha-2 receptors and can thus support an erection. A dose-dependent (20 to 60 mg) improvement in erection has been described. However, phentolamine is currently only used under clinical study conditions. Side effects include rhinitis, dizziness, and headache. The effectiveness is lower compared to apomorphine and sildenafil.

    Sildenafil (Viagra®)
    One of the most well-known active ingredients for the treatment of erectile dysfunction is sildenafil (Viagra®). The use of sildenafil is now seen as the therapy of choice for erectile dysfunction, especially since the safety of the drug has been tested in numerous clinical studies and the number of side effects is low. You can find a comprehensive treatise on the effects of the drug [here]. A list of the nitrates and NO donors available in Germany, the use of which can lead to dangerous interactions with the drug Viagra®, can be found [here]. You can read what German courts have to say regarding the assumption of costs [here].

    Ingestion of nitrates, NO donors (e.g. molsidomine)
    Retinitis pigmentosa
    Heart attack / apoplexy <6 months
    Hypotension <90/50 mm Hg
    Sickle cell anemia, leukemia, multiple myeloma (risk of priapism)
    Decompensated hepatopathy
    Non-compliance patients
    Severe fibrotic changes / curvatures in the penis
    Unstable angina pectoris, severe heart failure

    Side effects
    Headache 16%
    Facial redness 10%
    Indigestion 7%
    Swelling of the nasal mucosa 4%
    Visual disturbances 3%
    Dizziness 2%
    Rash 2%

    Tadalafil (IC351, Cialis ™) [Information for professionals]]
    This drug developed by Lilly Icos, like sildenafil, is one of the selective phosphodiesterase inhibitors (PDE 5 inhibitors). The drug was approved for Europe in November 2002. This drug has been approved in Germany since February 1st, 2003.

    Phase III studies with Cialis showed that men with moderate to severe erectile dysfunction achieved significantly better erections in 85% of the cases. Diabetics reported an increased erection in up to 64% of the cases. The most common side effects were headache, back pain, and dyspesia. Continue reading...

    Trazodone (Thombran®)
    This drug is a serotonin agonist with peripheral sympatholytic activity (alpha-receptor blocker) and is used as a non-tricyclic antidepressant. The effect is mediated by an inhibition of the serotonin reuptake and an alpha-receptor blockade. An increase in nocturnal erections was observed as a side effect. At a dose of 100 to 200 mg, 60% of the patients had an increase in erection, the best results being observed with psychogenic impotence. In combination with yohimbine, the success rate could be increased to 70%. In another study, the improved erection rate compared to placebo could not be proven. Regardless of these results, an effect could not be proven in placebo-controlled double-blind studies with a dose of 50-100mg in patients with mixed causes of erectile dysfunction.

    Vardenafil (Levitra ™) [Information for professionals]

    This drug developed by Bayer, like sildenafil, is one of the selective phosphodiesterase inhibitors. The drug has been approved in Germany since March 2003.

    According to the results of a phase II study, an 80% success rate was found, regardless of the age of the patient and the severity and etiology of the ED. The onset of action occurs after approx. 20-30 minutes. The half-life is around four hours.

    In a phase III study, 452 men with diabetes mellitus tested vardenafil for twelve weeks. 72% reported a better erection and 54% of the study participants had successful sexual intercourse after oral ingestion of 20 mg of the preparation. The most common side effects were headache, rhinitis and flushing.

    2. Injection and instillation materials

    Alprostadil, prostate aglandin E1, PGE1
    Alprostadil is used for SKAT therapy (cavernous body auto-injection therapy). This means that the patient uses a syringe to inject an optimized dose of the drug into the erectile tissue in order to achieve an erection. The success rate is 70 to 80% and therefore comparatively very high. Systemic side effects are hardly observed. An unpleasant side effect of overdose is priapism, the occurrence of erectile tissue fibrosis and local inflammatory and pain reactions have been described. You can find more information about SKAT [here].

    Alprostadil can also be used for topical application. The medication is introduced into the urethra (MUSE®) and from there diffuses into the blood vessels and reaches the corpus cavernosum. Here too, an individual adjustment to the dose is required. A dosage between 250 and 1000 µg is usual. The success rates achieved fluctuate between 30 and 66%, whereby the acceptance is quite high. Pain in the penis was a local side effect; systemic side effects were rare (dizziness). You can find more information about MUSE® [here].
    Phentolamine and papavarin combination preparation (Androskat®)
    The combination preparation has a synergistic effect compared to the effects of the individual substances. The effectiveness is very good at 60-75%. After testing the individual dose, prolonged erections are seen in 1% of all injections. Local problems with erectile tissue injection with this drug are described in 10-30% of cases. Due to the higher rate of prolonged erections compared to alprostadil, the drug is only used for PGE1 complications or in combination with PGE1 as a triple mix if it is ineffective on its own.

    3. Centrally active substances

    Apomorphine (Uprima®, IXense®)

    Mode of action
    Apomorphine is a substance active in the brain that stimulates special receptors (dopamine receptors [D1 and D2]) and was actually used as an emetic for poisoning. By stimulating the central D2 receptors in the paraventricular nucleus of the central nervous system (CNS), pathways that promote erection are activated. The advantage of apomorphine is also said to be the increased libido - the drug works in both healthy and impotent men, although other authors deny that it has an effect on libido. The drug only works in the presence of testosterone and oxytocin; it does not work, for example, on castrated men. The function of nitrite oxide synthesis both centrally and peripherally is a further prerequisite for the effectiveness of the drug. The latter also explains the fact that the effectiveness of apomorphine is weakened or canceled by NO synthesis inhibitors. Although the active ingredient can be detected in the blood just ten minutes after ingestion, the mean onset of action of apomorphine is after 18 to 19 minutes.

    Apomorphine is used as a sublingual tablet, which means that the tablet is placed under the tongue. There it dissolves and enters the bloodstream. The tablet should be taken about 20 minutes before sexual intercourse. Sexual stimulation is required for the drug to work. Consultation with a doctor is essential before use.

    In dose-finding studies, a sufficient erection was achieved in approx. 60% of the patients at a dose of 6 mg and only 2.7% reported the main side effect, nausea (the side effects are strictly dependent on the dose used).

    Recent clinical data show that in moderately to severely erectile dysfunctional patients, doses of 3 mg (as a sublingual tablet) have the most favorable risk-benefit ratio. About half of all patients achieved an erection sufficient for sexual intercourse. After the administration of 4 mg, the success was not significantly increased, but the rate of nausea increased significantly (14%).

    The currently recommended dosage is 2 to 3 mg. In this dosage, a good effect on erection formation is observed with only minor side effects.

    Side effect / tolerance
    So far, apomorphine has proven to be a well-tolerated and, above all, safe drug. Side effects at doses between 2 and 3 mg were mainly nausea (6.8%), headache (6.7%), dizziness (4.4%) and fatigue (1.9%). Syncope (sudden drop in blood pressure with loss of consciousness) is very rare at around 0.2%.

    Due to its mode of action, apomorphine can also be given to patients with the following secondary diseases: coronary heart disease (CHD), arterial hypertension, BPH, diabetes mellitus.

    The drug should not be given to patients with unstable angina pectoris, recent heart attack, severe heart failure and / or low blood pressure (hypotension) and intolerance.
    A melanocyte stimulating hormone
    The advantage of this centrally acting drug is that it can be applied under the skin (s.c.). This is important because many men fear the "injection into the penis" as used in SKAT.
    Naltrexone (Nemexin®)
    This drug is one of the opiate antagonists. In contrast to the well-known naloxone, the effect is stronger and longer-lasting. Placebo-controlled studies in men with non-organic ED showed improvement in morning erections, but no increases in libido and the number of intercourse.

    Yohimbine is a relatively selective antagonist of the alpha-2 receptors and acts in the central nervous system. Its effectiveness has already been examined in many studies. It is currently mainly used to treat psychogenic erectile dysfunction and has shown moderate improvement in erection compared to placebo.
    Mode of action
    Yohimbine is an iridoid indole alkaloid that acts as a centrally active alpha-adrenoceptor-2 antagonist. In this capacity, yohimbine acts on the circulatory system (lowering blood pressure, reflex tachycardia) and the urinary bladder (relaxation of: bladder neck, posterior urethra and prostate -> lowering the bladder outlet resistance). Yohimbine also has an effect on sexual behavior and was used as an aphrodisiac early on in West Africa. The beneficial side effect profile is advantageous with yohimbine. The main indication is fear of failure or moderate organic erectile dysfunction.
    Yohimbine works best for psychogenic impotence.
    The active ingredient is obtained from the bark of the yohimbine tree native to West Africa.
    For the first three days 3x5mg and then 3x10mg should be taken, whereby success is not to be expected before 14 days. The total duration of treatment extends over at least six weeks.
    Side effects
    Restlessness, dizziness, shaking hands, nasal congestion, trouble sleeping

    4. Hormones
    In addition to isolated deficiency, the male sex hormone is often prescribed as an additional empirical therapy or is a component of numerous aphrodisiacs. Testosterone influences central neurotransmitters (dopamine and serotonin) and thus intervenes in the formation of an erection. In healthy men, for example, there is an increase in the stiffness (rigidity) of nocturnal erections, whereas the frequency remains unchanged.
    Dehydroepiandrosterone (DHEA)
    This is a steroid hormone found in the adrenal cortex. It is a precursor to testosterone and cannot be obtained as a drug in the USA without a prescription. In a phase III study, an improvement in ED was described after taking 50 mg.

    5. Aphrodisiacs
    Aphrodisiacs are agents that strengthen the sexual instinct and potency. These are usually herbal active ingredients that have been in use for several thousand years. But drugs (hashish), alcohol and deadly nightshade also belong to this group due to their stimulating and disinhibiting effects. These also include substances that stimulate the urogenital system (parsley, celery) or increase the blood supply to the abdominal and sexual organs (basil, ginger, chilli). Muira puama or Maca, known as potency wood, also belong to this group. Continue reading...

    Operative treatment

    Surgical therapy for erectile dysfunction is carried out if all possible conservative therapeutic approaches have not led to success. The proportion is roughly between 5 and 10%. This step must be carefully thought out, as the surgical procedures, particularly the implantation of a penile prosthesis, lead to the destruction of the natural architecture of the penis. The sexual appetite, the ability to ejaculate and the experience of orgasm are not affected.

    Psychotherapy / partner therapy

    If organic causes are excluded and a psychogenic genesis is most likely, psychotherapeutic treatment should always be undertaken. The partner should be involved in the therapy.
    Sex counseling
    Sex education
    Behavior therapy
    Talk therapy