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Can’t Pee (Urinary Retention) Due To Drug Interaction!

If you need to urinate but can't pee, it is a medical emergency! Doctors call this urinary retention. It can be caused by common drugs.

Have you ever had trouble urinating? If you cannot empty your bladder, the discomfort can quickly become unbearable. Doctors call this condition “urinary retention.” A person experiencing this problem just says “I can’t pee!” It can come on gradually or, in the case of medications, turn into an acute crisis quite suddenly. That’s what happened to this reader.

What Do You Do When You Can’t Pee in the Middle of the Ocean?

This reader was surrounded by water, but he could not urinate:

Q. I recently experienced a traumatic drug interaction on a cruise. While being treated for a sinus infection, I was advised to take behind-the-counter Sudafed. I started taking it four days before leaving on the cruise.

On the first day of the cruise, I put on a motion sickness patch (scopolamine), as I have done many times before. At 65, I’m sure my prostate isn’t what it used to be, but I’ve never had any problems before.

It turns out that these drugs can shut off urine flow when taken together. I spent an agonizing night trying to void my bladder and later ended up in the ship’s infirmary with a catheter. Maybe my story will help others avoid this crisis.

A. You got hit with a double whammy. Behind-the-counter Sudafed contains pseudoephedrine as its active ingredient. This decongestant drug shrinks blood vessels in the nose to make breathing easier. But it also causes the smooth muscle at the outlet of the bladder to contract. This makes it harder to urinate.

Add to that the scopolamine patch (Transderm Scop) to prevent sea sickness, and you have a recipe for disaster. That’s because the anticholinergic activity of scopolamine also interferes with normal urination. Double Trouble! No wonder you needed a catheter.

Your physician and pharmacist might have anticipated this interaction. It always makes sense to ask about the possibility of drug incompatibility, especially when traveling!

Can’t Pee? Could It Be Your Medicine(s)?

There are a surprising number of drugs that can make it harder to urinate.

Anticholinergic Medications:

As mentioned above, drugs with anticholinergic activity can be problematic. What, you may ask, does “anticholinergic activity” mean? Good question!

Here is the executive summary on a critical neurotransmitter called acetylcholine (ACh, pronounced ASS-se-TEEL-kol-EEN). For one thing it enables your muscles to contract. You could not pick up a pencil without Ach. It is a messenger between brain and muscle. It is also critical for brain function. Without ACh stimulating neurons in the brain you would have a terrible time thinking or remembering.

Medications that interfere with acetylcholine (anticholinergic drugs) contribute to cognitive impairment. People forget things that they should remember. Two classic anticholinergic drugs are scopolamine and atropine.

According to StatPearls (May 8, 2023), anticholinergic drug side effects include:

“Common central anticholinergic adverse effects include headache, impaired memory, reduced cognitive function, behavioral disturbances, anxiety, and insomnia at low dosages.”

In the body, (aka peripheral) adverse drug effects include:

• Dry mouth, eyes and skin (reduced sweating)
• Rapid heart rate, flushing and irregular heart beats
• Reduced digestive tract contractions, constipation
• Blurred vision, dilated pupils
• Reduced muscle contractions

What Drugs Have Anticholinergic Activity?

Very few health care professionals are aware of which drugs have anticholinergic activity. Most would know, however, that atropine and scopolamine are anticholinergic.

Physicians are taught in medical school that such drugs are often used for problems within the digestive tract such as irritable bowel syndrome, diverticulitis and diarrhea. In such cases, the medications are often referred to as antispasmodics.

But there are scores of other medications that also have anti-ACh activity. If you are interested, here is a link you may find helpful.

Anticholinergic drugs are prescribed for overactive bladder and incontinence, motion sickness, dizziness, symptoms of Parkinson’s disease and breathing problems like asthma and COPD (chronic obstructive pulmonary disease). Many health professionals are unaware that some drugs for depression, anxiety, hypertension, heartburn and mental illness also have anticholinergic activity.

Other Reasons People Can’t Pee: Urinary Retention:

People who complain that they can’t empty their bladders may be suffering from any of a number of medical conditions. Many older men have enlarged prostate glands. That can lead to pressure on the urethra (the tube that carries urine). Starting urine flow can be difficult and such blockage can also reduce the stream of urine. The bladder may not empty completely after urination.

Women can also experience urinary retention. That can be brought on by a sagging bladder (cystocele). Scar tissue can also contribute to narrowing of the urethra. Urinary tract infections may also add to the problem.

A nervous system disorder or nerve damage may lead to urinary retention. That can include Parkinson’s disease (PD), cauda equina syndrome, MS, diabetes or stroke. Some other conditions that can contribute to this problem are urinary tract stones (calculi), prostatitis or severe constipation.

How Would You Know If Your Medications Mean You Can’t Pee?

Medications should always be ruled out before someone is referred for catheterization or surgery. Here is one example of how a medication could contribute to the problem:

Bernadette was put on antihistamines that might have anticholinergic activity. Diphenhydramine (the ingredient in Benadryl and most all “PM” pain relievers) is notorious for anti-ACh side effects.

Here is her story:

“A couple of years ago I had two urinary tract infections within a period of a couple of months. I’m pretty sure they were caused by antihistamines. My eye doctor had recommended taking an antihistamine each day, whether I needed it or not, to prevent itchy eyes during seasonal allergy time. I think the antihistamine caused urinary retention, which led to the UTI’s.

“Now I’m careful with antihistamines and take the smallest amount, and only as needed. Also, I try to be aware when I might be experiencing urinary retention. Also, I do take a cranberry pill that also contains a probiotic, Vitamin C and calcium. Knock on wood; I haven’t had a UTI since”

Final Words If You Can’t Pee:

Because there are so many possible causes of urinary retention, it is essential to get a proper diagnosis. That is especially true if someone experiences sudden onset urinary retention. If you can’t pee, that is a medical emergency, as our reader taking scopolamine AND pseudoephedrine (Sudafed) discovered.

Have you ever experienced urinary retention? What was it like? Please share your experience in the comment section below. And if you think this article might be of interest to someone you know, please share it. We are grateful for your support.

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About the Author
Joe Graedon is a pharmacologist who has dedicated his career to making drug information understandable to consumers. His best-selling book, The People’s Pharmacy, was published in 1976 and led to a syndicated newspaper column, syndicated public radio show and web site. In 2006, Long Island University awarded him an honorary doctorate as “one of the country's leading drug experts for the consumer.”.
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