Difficulty staying hard is one of the most common sexual health issues men experience, and it rarely has anything to do with how attracted he is to you. Between 5% and 10% of men under 40 deal with erectile difficulties, and the numbers climb steadily with age. The causes range from stress and anxiety to blood flow problems and medication side effects, and most of them are treatable once identified.
How Erections Work (and Where They Fail)
An erection depends on blood flowing into the penis and staying trapped there. The arteries dilate, spongy tissue fills with blood, and veins compress to keep it in place. This entire process is driven by a signaling molecule called nitric oxide, which relaxes blood vessel walls and allows them to open up. Anything that disrupts blood flow, nerve signaling, or hormonal balance can cause the erection to weaken or disappear partway through sex.
Losing an erection occasionally is normal. Doctors only consider it a medical issue when it happens consistently, defined as a recurrent inability to maintain an erection sufficient for sexual satisfaction. If it’s happening most of the time rather than once in a while, something specific is usually driving it.
Stress and Performance Anxiety
This is the most common cause in younger men, and it creates a frustrating cycle. When your boyfriend feels anxious about staying hard, his body activates its “fight or flight” response. That response is designed to redirect energy toward survival: heart rate increases, breathing deepens, and functions the body considers non-essential (like maintaining an erection) get shut down. It’s an unconscious process he can’t override with willpower.
If the anxiety becomes ongoing, the body starts producing elevated levels of cortisol, the primary stress hormone. Cortisol suppresses testosterone, which is responsible for sex drive and contributes to the blood flow changes that sustain an erection. So chronic stress, whether from work, finances, relationship tension, or the bedroom itself, can create a hormonal environment that actively works against him. The more he worries about losing his erection, the more likely it is to happen, which feeds more worry.
Physical Health Conditions
Erectile difficulty is often an early warning sign of cardiovascular problems. Because the blood vessels in the penis are smaller than those in the heart, they tend to show signs of damage first. Conditions that compromise blood flow are the most common physical culprits:
- Heart and blood vessel disease. Atherosclerosis (plaque buildup in arteries), high blood pressure, and high cholesterol all reduce the body’s ability to deliver blood where it needs to go.
- Diabetes. Over time, elevated blood sugar damages both blood vessels and nerves, making it harder to achieve and maintain erections.
- Obesity. Excess weight contributes to inflammation, hormonal imbalance, and reduced cardiovascular fitness, all of which affect erectile function.
- Nerve damage. Conditions like multiple sclerosis, spinal cord injuries, or damage from pelvic surgery can interrupt the signals between the brain and the penis.
If your boyfriend is in his 20s or 30s with no known health conditions, a physical cause is less likely but not impossible. If he’s in his 40s or older, the odds shift. About 22% of men at age 40 experience moderate to significant erectile dysfunction, rising to 49% by age 70.
Low Testosterone
Testosterone plays a direct role in both sex drive and the ability to maintain an erection. Levels below 300 nanograms per deciliter are considered low, and the most telling symptoms are sexual: reduced libido, loss of morning erections, and difficulty staying hard during sex. Low testosterone can result from aging, chronic stress, obesity, sleep problems, or underlying medical conditions like thyroid imbalance. A simple blood test can confirm it.
Alcohol, Smoking, and Inactivity
Heavy drinking is one of the most common and overlooked causes. Excessive alcohol creates inflammation that damages the lining of blood vessels and reduces nitric oxide availability, the molecule that makes erections possible in the first place. A couple of drinks might lower inhibitions, but more than that actively works against blood flow to the penis.
Smoking is a well-established risk factor. Nicotine constricts blood vessels and damages their inner lining over time. Research shows that men who quit smoking experience measurable improvements in both physiological erectile function and their own perception of their sexual health.
A sedentary lifestyle compounds these effects. Regular physical activity improves cardiovascular fitness, enhances blood vessel function, and increases nitric oxide production. Men who exercise consistently have significantly lower rates of erectile problems than those who don’t.
Medications That Interfere
Several common prescription drugs can cause or worsen erection problems. The most frequent offenders include:
- Antidepressants. SSRIs and other psychiatric medications are well known for causing sexual side effects, including difficulty staying hard and reduced desire.
- Blood pressure medications. Thiazide diuretics (water pills) are the most common cause in this category, followed by beta-blockers.
- Anti-anxiety medications. Benzodiazepines and similar drugs can dampen sexual response.
- Antihistamines. Even over-the-counter allergy and stomach acid medications can contribute.
- Opioid painkillers. These suppress testosterone production and reduce sexual function broadly.
- Hair loss treatments. Finasteride, commonly prescribed for male pattern baldness, is a known cause.
If your boyfriend started a new medication around the time the problem began, that connection is worth exploring with his doctor. Switching to a different drug in the same class often resolves it.
What Treatment Looks Like
The first step is figuring out whether the cause is primarily physical, psychological, or a combination. A doctor can check blood pressure, blood sugar, cholesterol, and testosterone levels through routine tests. If the issue is situational (it happens with a partner but not during sleep or masturbation), that points toward a psychological component.
Oral medications that improve blood flow to the penis are the standard first-line treatment and work for about 60% to 70% of men. They don’t create arousal on their own but help maintain an erection once arousal begins. For the roughly 30% to 40% of men who don’t respond well to pills, other options exist, including injectable treatments and, in more severe cases, implantable devices that restore function for over 90% of recipients.
For anxiety-driven erectile problems, the most effective approaches often don’t involve medication at all. Therapy focused on reducing performance pressure, mindfulness techniques, and gradual exposure to sexual situations without the expectation of intercourse can break the anxiety cycle. Couples therapy can also help when relationship dynamics are contributing to the problem.
How to Talk About It
The way you bring this up matters more than you might think. Performance anxiety feeds on shame, so anything that makes him feel broken or inadequate will likely make things worse. Harvard Health recommends having the conversation outside the bedroom, at a time when neither of you feels vulnerable, rather than in the moment when emotions are raw.
Be direct but compassionate. Let him know you care about him, not just the erection. Remind him (and yourself) that this is a common, treatable condition that affects millions of men and has nothing to do with his desire for you. Framing it as a health issue you want to help him address, rather than a sexual failure, gives him room to take action without defensiveness.
Expanding your definition of sex beyond penetration also reduces the pressure significantly. When an erection isn’t the sole measure of a successful sexual encounter, the stakes drop, and paradoxically, that often makes the erection more likely to cooperate.