Difficulty getting or keeping an erection is one of the most common sexual health problems men experience, affecting an estimated 20 to 30 percent of men between ages 40 and 70, and more than half of men over 70. If it’s happening to you, the cause is almost always identifiable, and in most cases treatable. The explanation comes down to blood flow, nerve signaling, hormones, or psychological factors, often a combination of more than one.
How Erections Actually Work
An erection depends on a precise chain of events. When you’re aroused, nerve signals trigger the release of a gas molecule called nitric oxide inside the tissue of the penis. Nitric oxide relaxes the smooth muscle in the walls of blood vessels, allowing them to widen and fill with blood. That blood gets trapped under pressure, creating firmness. Anything that disrupts this process, whether it’s restricted blood flow, damaged nerves, low hormone levels, or mental distraction, can prevent a full erection or cause one to fade too quickly.
Blood Vessel Problems Are the Most Common Cause
The single most frequent physical reason for erection problems is poor blood flow, and it starts with damage to the inner lining of blood vessels (the endothelium). When this lining stops functioning properly, blood can’t flow freely to the penis. Over time, plaque builds up inside the arteries, a process called atherosclerosis, which narrows them further.
This is the same process that leads to heart disease. In fact, erection problems are often an early warning sign of cardiovascular trouble, because the arteries in the penis are smaller than those supplying the heart and get blocked sooner. High LDL cholesterol, high blood pressure, smoking, and a sedentary lifestyle all accelerate this damage. If you’re under 50 and noticing erection problems without an obvious psychological trigger, it’s worth having your cardiovascular health checked.
Stress and Anxiety Can Shut Things Down
Your nervous system has two competing modes: one that relaxes you (parasympathetic) and one that activates your fight-or-flight response (sympathetic). Erections require the relaxation side to dominate. When you’re anxious, stressed, or fixated on whether you’ll perform, your body stays in fight-or-flight mode and releases the stress hormone cortisol.
In men without anxiety, cortisol levels naturally drop at the start of sexual arousal, which allows the relaxation response to take over. In men dealing with performance anxiety or chronic stress, cortisol stays elevated because the sympathetic nervous system keeps firing. This directly inhibits the process that causes blood vessels to relax and fill. The frustrating irony is that worrying about erection problems makes them worse, which creates a cycle that can be hard to break without deliberate intervention like therapy or mindfulness-based techniques.
Low Testosterone
Testosterone plays a supporting role in erections by maintaining sex drive and helping the signaling process work properly. The American Urological Association defines low testosterone as a total level below 300 ng/dL. Men below that threshold are significantly more likely to experience erection difficulties, and the risk increases as levels drop further. Men with levels under 231 ng/dL have roughly twice the odds of developing problems compared to men with normal levels.
Low testosterone becomes more common with age, but it can also result from obesity, sleep apnea, opioid use, or certain medical conditions. Symptoms beyond erection problems include fatigue, reduced muscle mass, low mood, and decreased interest in sex. A simple blood test can check your levels.
Diabetes and Nerve Damage
Chronically high blood sugar damages both nerves and blood vessels over time, which is why diabetes is one of the strongest risk factors for erection problems. The nerve damage (neuropathy) reduces sensation and weakens the signals that trigger nitric oxide release. The blood vessel damage restricts flow on top of that. Men with diabetes who keep their blood sugar well controlled have a significantly lower risk of developing these complications, so management matters even if the damage has already started.
Medications That Interfere
A surprisingly long list of common medications can cause or worsen erection problems. The most notable categories include:
- Blood pressure medications: Thiazide diuretics (water pills) are the most common culprits, followed by beta blockers. Alpha blockers tend to cause fewer issues.
- Antidepressants: SSRIs like fluoxetine and sertraline are well known for sexual side effects, as are older tricyclic antidepressants and anti-anxiety medications like diazepam and lorazepam.
- Antihistamines: Over-the-counter options like diphenhydramine (Benadryl) and heartburn medications like cimetidine and ranitidine can contribute.
- Hair loss and prostate medications: Finasteride, sold for both hair loss and enlarged prostate, is linked to erection problems in some men.
If your erection problems started around the same time you began a new medication, that timing is worth discussing with whoever prescribed it. Alternatives within the same drug class often have fewer sexual side effects.
Lifestyle Factors That Make a Difference
Exercise is one of the most effective non-drug interventions. A review of the evidence found that men who did aerobic exercise for 30 to 60 minutes, three to five times per week, saw meaningful improvements in erectile function, in some cases comparable to what medications provide. The benefit comes from improved blood vessel health, lower blood pressure, better cholesterol, and reduced stress hormones.
Smoking is particularly damaging because it directly injures the blood vessel lining. Quitting leads to measurable improvement in vascular function within weeks. Heavy alcohol use suppresses testosterone and impairs nerve function. Obesity raises the risk through multiple pathways: it increases inflammation, promotes insulin resistance, and converts testosterone to estrogen in fat tissue. Losing even a moderate amount of weight can noticeably improve erection quality for men who are overweight.
How Treatment Works
The most widely prescribed medications for erection problems are PDE5 inhibitors, which work by boosting the effect of nitric oxide and keeping blood vessels relaxed longer. The three main options differ in practical ways. Sildenafil works within about 14 minutes for roughly a third of men and lasts around four hours. Tadalafil takes slightly longer to kick in but lasts much longer, with a half-life of 17.5 hours, making it useful for more spontaneous timing. Vardenafil falls somewhere in between. One practical difference: eating a fatty meal slows down sildenafil and vardenafil, but doesn’t affect tadalafil.
These medications don’t create arousal on their own. They make the physical response possible when arousal is present. For men whose problems are primarily psychological, cognitive behavioral therapy or sex therapy often works well, sometimes combined with short-term medication use to break the anxiety cycle. For men with low testosterone, hormone replacement can restore function when levels are genuinely deficient.
When It’s Occasional vs. Ongoing
Occasional difficulty is normal and happens to nearly every man at some point. Fatigue, alcohol, distraction, and stress can all cause a one-off failure that doesn’t signal anything deeper. The distinction that matters is pattern. If you’re consistently unable to get or maintain an erection firm enough for sex over a period of weeks or months, something physiological or psychological is likely contributing. If you still get erections during sleep or in the morning but not during sex, that points more toward a psychological cause, since the physical machinery is clearly working. If erections are weak or absent across all situations, a physical cause is more likely.