Does Metformin Cause Erectile Dysfunction? Separating Fact From Fear

What metformin is

Metformin is one of the most prescribed medicines in the world. It is a generic pill used to treat type 2 diabetes and sometimes prediabetes or polycystic ovary syndrome. It lowers blood sugar mainly by telling the liver to make less glucose and by helping muscles use insulin better.

It has been used since the 1950s in Europe and was approved by the FDA in 1994. Its main side effects are stomach upset and, with long use, lower vitamin B12 levels. Erectile dysfunction (ED) is not listed as a side effect on the FDA label.

Still, the question comes up often because so many men who take metformin also have ED. Let us look at why.

The real culprit: diabetes itself

Men with diabetes are about three times more likely to have ED than men without it, and it tends to show up 10 to 15 years earlier. High blood sugar damages the small blood vessels and nerves that erections depend on. It also lowers nitric oxide, the chemical that opens blood vessels during arousal.

Diabetes usually travels with other ED causes: high blood pressure, high cholesterol, obesity, low testosterone, and depression. Each adds its own damage.

So when a man starts metformin and later notices ED, the most likely explanation is that the diabetes that led to the prescription is the same diabetes that is harming his erections. The timing can look like cause and effect when it is not.

What the research says about metformin specifically

There is no large randomized trial showing metformin causes ED. Most of what we have is observational, which means researchers looked at groups of men and found patterns, not proof.

A 2017 review in a sexual-medicine journal looked at diabetes drugs and sexual function. It found some studies where men on metformin had lower testosterone and lower sex drive compared with men on other diabetes drugs, but the studies were small and mixed. A few case reports describe ED that started with metformin and improved when it was stopped.

On the other side, several studies suggest metformin may help erections by improving blood vessel function and insulin sensitivity. A 2024 Mendelian randomization study, which uses genetics to test cause and effect, found no causal link between metformin and ED. The honest summary: metformin is probably not a major cause of ED, but a small number of men may notice a change.

The testosterone question

Some small studies found that metformin lowered total testosterone by a modest amount in men with metabolic syndrome. Others found no change or even an increase as weight came down. Testosterone also drops naturally with age, obesity, and poor sleep, so it is hard to pin on one pill.

Low testosterone contributes to ED mostly by lowering desire and energy, though very low levels can reduce erection quality too. If you take metformin and have low libido, fatigue, or ED, a simple morning blood test can tell you where your testosterone stands.

A Zen IV nurse can draw labs at your home in New York and New Jersey, including total and free testosterone, A1C, lipids, and vitamin B12, so you and the medical director can see the full picture instead of guessing.

What to do if you take metformin and have ED

Do not stop metformin on your own. Uncontrolled blood sugar is far worse for erections than the pill is. Talk to your prescriber about any concern.

Get the basics checked: A1C, blood pressure, cholesterol, testosterone, and B12. Fixing those often improves erections more than any single medicine change.

Consider ED treatment directly. PDE5 inhibitors like sildenafil (the generic of Viagra) and tadalafil (the generic of Cialis) work well in men with diabetes, though sometimes a higher dose is needed. They are safe to take with metformin.

Habits that help erections and blood sugar at once

Weight loss improves both. Even losing 5 to 10 percent of body weight raises testosterone, improves insulin sensitivity, and improves erectile scores in studies of men with obesity. GLP-1 medicines like compounded semaglutide ($199 per month) and compounded tirzepatide ($299 per month at Zen IV Spa; neither is FDA-approved) can help men who have struggled with diet alone.

Aerobic exercise improves erectile function in randomized trials and lowers blood sugar within hours. Quitting smoking and cutting alcohol help blood flow.

Sleep seven hours or more. Short sleep raises blood sugar and lowers testosterone, which hurts both the diabetes and the ED.

Get a clear answer about your ED

If you take metformin and are dealing with ED in New York or New Jersey, book a free video visit. Our medical director can review your medicines, order home labs, and start an ED program for $129 if it fits. Learn more at /sexual-wellness/ or call (332) 239-2005.

Common Questions

Sources: FDA prescribing information for metformin (Glucophage, 2018); review of diabetic pharmacotherapy and sexual function, Sexual Medicine Reviews 2017; Mendelian randomization study of antidiabetic drugs and ED, 2024; review of metformin and male reproductive function, Frontiers in Endocrinology 2021.

All treatments are medical services. Every guest is screened, and every treatment is prescribed by a licensed provider. Nothing on this page is medical advice for you personally, and the opinions summarized here belong to the doctors named, not to Zen IV Spa. Talk to a provider before starting or stopping anything.