Why You Cannot Pee On Heroin

Clear Treatment

I’m having trouble peeing

Urine retention is an inability to pee, and we get it, this is not an exciting topic to read about. However, it’s one of the most common complaints from heroin users. That begs the question. Why do heroin addicts have a trouble peeing? That’s what this page will answer.

Normal urination

It would be difficult to fix a broken television unless you understand what an unbroken television was supposed to do. Following that logic, it’s important to understand normal urination, so that you can fully understand abnormal urination.

Normal urination requires two separate events to occur simultaneously.

  1.  The nervous system must excite the muscle surrounding the bladder in order to contract the bladder.
  2.  The nervous system must relax the sphincter muscles within the outflow tract of the bladder so that urine can escape.

When the bladder contracts and the urethral muscles relax we urinate.

Bladder and Kidneys

The primary reasons why heroin makes it difficult to urinate is linked to functional changes within two organs in the body. These two organs are the bladder and the kidneys.


Heroin use relaxes the detrusor muscle that surrounds the bladder, which increases bladder capacity by 20 – 65 percent. At the same time heroin use inhibits the parasympathetic nervous system, which decreases the sensation of bladder fullness. Lastly, it tightens both internal and external urethral sphincters, which increases resistance through the outflow tract of the bladder.


Everyday, our kidneys filter about 135 quarts of blood to produce about 1 1/2 quarts of urine. But when a person uses heroin, the brain tells the pituitary gland to release ADH (antidiuretic hormone). ADH tells the kidneys to reabsorb water from urine and move it back into the bloodstream. This tends to make urine much darker, because it’s more concentrated, i.e. there are more solutes and less water.

Can’t pee after using heroin

The combination of decreased water in urine, increased bladder capacity, decreased sensation of bladder fullness and increased outlet resistance results in an uncomfortable problem whereby people who use heroin cannot pee.
We know now that intravenous heroin users are more likely to experience higher rates of urine retention as compared with heroin sniffers and smokers. In addition, short half-life opioids such as heroin generally have less urine retention as compared to longer half-life opioids, such as Methadone. In other words, heroin wears off quickly while Methadone does not.

Glossary – Terms


  1. The urethral sphincters: These two muscles control the release of urine. The external urethral sphincter and the internal urethral sphincter. When either of these muscles contracts, the urethra is sealed shut.


  1. The detrusor muscle: is a smooth muscle found in the wall of the bladder that remains relaxed to allow the bladder to store urine but contracts during urination to help release urine.


  1. The guardian reflex: Is a neurophysiological reflex that inhibits a person from urinating without consent. In other words the guardian reflex’s purpose is to allow the bladder to fill without having an accident. It inhibits contraction of the detrusor muscle, while simultaneously contracting the external sphincter.