Last week, my husband fainted while urinating. His doctor said he might have micturition syncope. What causes this, and what can he do about it?

Answer From Phillip A. Low, M.D.

Micturition (or post-micturition) syncope is fainting during or, more commonly, immediately after urination due to a severe drop in blood pressure. Micturition syncope is most common in older men and usually occurs at night after a deep sleep.

The exact cause of micturition syncope isn't fully understood. But it may be related to opening (vasodilation) of the blood vessels that occurs when getting up and standing at the toilet or that occurs at the rapid emptying of a full bladder. This is thought to result in a sudden drop in blood pressure.

Other factors that may play a role in micturition syncope include:

  • Alcohol
  • Hunger
  • Fatigue
  • Dehydration
  • Medical conditions, such as a respiratory infection
  • Use of alpha blockers to improve urination in men with prostate problems

Preventing micturition syncope

Micturition syncope is uncommon and should be evaluated by a doctor because it may indicate an underlying medical condition. Prevention of micturition syncope depends on recognizing the factors that contribute to micturition syncope and avoiding them.

Some strategies you might suggest to your husband to avoid micturition syncope and possible resulting injury are:

  • Avoid excessive drinking of alcohol
  • Don't get out of bed suddenly — first, sit on the edge of the bed and move your legs, making sure you aren't dizzy or lightheaded
  • Urinate sitting down
  • Ask your doctor whether any medications you're taking may be causing your condition

As much as possible, ensuring the floor from your bed to the bathroom is carpeted or padded also is a good strategy for avoiding injury from a potential fall.


Phillip A. Low, M.D.

Get the latest health information from Mayo Clinic’s experts.

Sign up for free, and stay up to date on research advancements, health tips and current health topics, like COVID-19, plus expertise on managing health.

To provide you with the most relevant and helpful information, and understand which information is beneficial, we may combine your email and website usage information with other information we have about you. If you are a Mayo Clinic patient, this could include protected health information. If we combine this information with your protected health information, we will treat all of that information as protected health information and will only use or disclose that information as set forth in our notice of privacy practices. You may opt-out of email communications at any time by clicking on the unsubscribe link in the e-mail.

April 17, 2020 See more Expert Answers