Medically reviewed by Dr. Meinolf Dorka, Medical Director, last reviewed September 2026
One of the first questions people ask themselves about erectile dysfunction is not what to do about it, but why it is happening. That question is worth taking seriously, because the cause usually points to the answer. It is also worth asking without dread. In most cases the reasons are common, understandable, and treatable.
Erectile dysfunction, often shortened to ED, means trouble getting or keeping an erection firm enough for sex. This is a plain guide to what lies behind it, split into the physical and the psychological, and to how the two so often work together.
If this is weighing on you
Occasional worry is ordinary. If you are struggling, support is available. In an emergency, or if you or someone else is in immediate danger, call 144 for medical help or 117 for the police. For emotional support, 143 (Die Dargebotene Hand) is available 24 hours a day in German, French, and Italian; support in English is available through Heart2Heart on 0800 143 000, daily from 18:00 to 23:00. For children and young people, 147 offers support. ahtida Health is not an emergency service.
The short version
The causes of ED fall into two broad groups: physical, to do with the body, and psychological, to do with mood, thoughts, and stress. Often both are at work at the same time. The World Health Organization places it among conditions related to sexual health. Neither group is more legitimate than the other; what matters is which applies to you, and that is what an assessment is for.
Physical causes
An erection depends on healthy blood flow, working nerves, balanced hormones, and enough relaxed arousal to set it all in motion. A problem with any of these can show up as ED, which is why the physical causes are broad.
The most common thread is circulation. An erection is largely a matter of blood arriving and staying put, held in by valves inside the penis, so anything that narrows or stiffens blood vessels can interfere: heart disease, atherosclerosis, high blood pressure, and high cholesterol among them. Diabetes is a particularly common contributor, through its effect on both blood vessels and nerves. Obesity and the cluster of changes that often travel with it add to the risk.
Other physical causes include hormonal changes such as low testosterone; neurological conditions and nerve damage, for example after a stroke or from multiple sclerosis; injuries or surgery affecting the pelvis, prostate, or spinal cord; and Peyronie’s disease, which changes the shape of the penis.
Hormones deserve a specific note. Low testosterone can reduce desire and contribute to ED, and less commonly, thyroid problems or a raised level of the hormone prolactin can play a part. These are checked with a simple blood test where there is a reason to suspect them, which is one of the things a first assessment can sort out.
Certain medicines can cause or worsen ED as a side effect, including some antidepressants, anti-anxiety medicines, blood pressure medicines, diuretics, and antihistamines. This is worth one firm point of caution: if you suspect a medicine is behind your ED, do not stop or change it on your own. Speak to the doctor who prescribed it, who may be able to adjust the dose or suggest an alternative.
Lifestyle and daily habits
Some of the most common contributors to ED sit in everyday habits, which is worth knowing because they are also the most changeable. Smoking is a clear risk factor, because it damages blood vessels over time and blood flow is central to an erection. Heavy or regular alcohol use works against things in two ways, dampening arousal in the moment and, over the longer term, affecting nerves and hormones. A lack of physical activity, excess weight, and poor sleep each raise the odds, partly through their effect on blood pressure, blood sugar, and testosterone. Recreational drugs can contribute as well. None of these guarantees ED, and none makes it your fault; they are simply levers that often help when they are adjusted.
When ED is a signal, not just a symptom
There is one physical link that deserves its own mention. Erectile dysfunction can be an early sign of a problem with the heart and blood vessels, because the arteries that supply an erection are small and often show strain before larger ones do. In practice, this means ED is sometimes the first noticeable hint of something like high blood pressure or narrowing arteries. That is not a reason to panic. It is a reason to have it looked at, because doing so can be good for more than your sex life.
Psychological causes
The brain starts an erection, so anything that gets in the way of feeling relaxed and aroused can get in the way of the erection itself. The common psychological contributors are stress, anxiety, depression, low self-esteem, poor body image, guilt, difficulties within a relationship, and, for some people, the effects of past trauma.
Performance anxiety deserves a specific mention, because it can create a loop. One difficult experience leads to worry about the next, the worry makes an erection harder to reach, and the difficulty then feeds the worry. The loop is real, and it is also one of the more responsive things to address once it is named.
Depression deserves a particular note, because the link runs both ways: it can dampen desire and interfere with arousal, and living with ED can in turn lower mood. The same is true of stress that has nothing to do with sex at all, because money, work, and poor sleep can spill over into the bedroom without any physical cause being present.
Relationships matter here too, in both directions. Tension, unspoken resentment, or a fear of disappointing a partner can all feed into difficulty, and difficulty that is not talked about can in turn strain a relationship. Broader pressures play a part as well, including the quiet expectation that sex should always work on demand, which sets a standard nobody meets every time. Naming that expectation for what it is often takes some of the weight off.
If this is where you recognise yourself, hold onto one thing: a psychological cause is not a character flaw, and it is not imagined. The body and the mind are not separate systems here, and a difficulty that starts in the mind is information, not failure.
When it is a bit of both
The neat split between physical and psychological is useful, but the honest picture is messier, because the two can interact. A small physical change can slow your response, worry about that change can add to it, and before long it is hard to say where one ends and the other begins. That is normal. It simply means a good assessment looks at both, and that you do not need to have worked out the answer before you ask.
How a doctor sorts out the cause
Because the causes are broad, working out which apply to you is the point of a first assessment, and it is usually more straightforward than people expect. A doctor will typically start with questions about your general health, your mood and stress levels, any medicines you take, and how and when the difficulty shows up. A brief physical check and a few routine blood tests, for things like blood sugar, cholesterol, and testosterone, often fill in the rest. From that, a doctor can usually tell whether the picture is mainly physical, mainly psychological, or a mix, without anything invasive. You can decline any test you are not comfortable with.
What the cause means for what comes next
Knowing the cause matters because it shapes the response. Treating ED that comes from high blood pressure looks different from treating ED that comes from performance anxiety, and often the most useful first step is treating the underlying issue rather than the erection alone. It is also why two people with the same symptom can be offered quite different plans.
It is fair to want to know how long that will take. Here honesty serves you better than reassurance: no responsible clinician will promise a timeline before understanding the cause. What can be offered is an assessment, a plan that fits what is found, and a point at which it is reviewed.
How do you get support in Switzerland?
A doctor is a good place to start: a GP, or a urologist. A first Consultation is often mostly questions and a brief physical check, and sometimes a few routine blood tests to look for things like diabetes, cholesterol, or low testosterone.
If you would rather begin more privately, ahtida Health is a structured digital medical clinic that includes sexual health among its areas of care, with Consultations available in German and English. You can learn more about sexual health care before deciding anything.
A note that applies throughout: ahtida Health is not an emergency service. For a medical emergency in Switzerland, call 144.
Frequently asked questions
Can my medication be causing ED?
Is it physical or all in my head?
Does ED mean I have a heart problem?
Can stress on its own cause ED?
I am young and healthy. Why is this happening?
Does getting older cause ED by itself?
Can more than one thing be causing it?
Understanding it is the first step
Erectile dysfunction usually has a reason, and the reason is usually something that can be understood and worked with. If you now have a clearer sense of what might be behind it, you have what you need to decide whether the next step is worth taking, in your own time.
When you are ready, you can talk it through with a doctor. It is simply a chance to understand what may be happening and explore your options.
References
World Health Organization. ICD-11 for Mortality and Morbidity Statistics: Male erectile dysfunction (HA01.1). 2025.
Cleveland Clinic. Erectile Dysfunction (ED). Last updated 28 August 2023.
Mayo Clinic. Erectile dysfunction: Symptoms and causes. 1 March 2025.
ch.ch. Emergency numbers (Switzerland). 2026.
Die Dargebotene Hand / Tel 143. Contact and language coverage. 2026.
Urology Care Foundation. Erectile Dysfunction (ED). Date not stated on page.
Erectile Dysfunction. In: Skinner MK, ed. Encyclopedia of Reproduction. 3rd ed. Academic Press; 2025.