With cold and flu season in full swing, experts are warning men who have an enlarged prostate to avoid medicines containing antihistamines and decongestants. 

“It’s very important that men with enlarged prostate avoid cold medicines with pseudoephedrine or phenylephrine. Those are ingredients in decongestants and they constrict the prostatic capsule” and lead to urine retention, said Dr. Gregory T. Bales, a urologist at the University of Chicago Medical Center. “Antihistamines aren’t quite as bad, because they work more on the bladder muscle, but they can cause bladder contractility.”

Enlargement of the prostate, formally known as benign prostate hyperplasia (BPH), results from increased cell growth in and around the prostate gland. The increased growth can constrict the urethra (the tube that carries urine out from the bladder) and decrease urine flow. Men with the progressive disease often have difficulty urinating and the urge to go more frequently.

BPH is more common in older men, because as men age their prostate continues to grow. Nearly 80 percent of men age 50 and older will be diagnosed with some degree of the disease, said Dr. William Catalona, a urologist with Northwestern University’s Feinberg School of Medicine in Chicago.

“We don’t know what causes benign prostatic enlargement, it’s one of the great mysteries, and we really wish we did because it’s such a prevalent condition,” Catalona told Reuters Health. “Sometimes men need to get up every hour at night.”

Bales has treated hundreds of patients struggling with BPH, and he warns against waiting too long to visit a doctor during complete retention. Severe retention can cause kidney damage and other serious issues.

“If a man is already having a little difficulty and his stream is already slow, and then you (make it worse) it by adding one of these medicines, it’s the recipe for causing retention. All it takes is one dose,” Bales told Reuters Health. “If you haven’t urinated in six hours or so, you have to go to the hospital and get a catheter put in to drain that liquid. Then we wait a couple days to let the medicine get out of his system and then do a urine test. It’s painful.”

Cold remedies that are inhaled, such as a nasal corticosteroid, will not have the same side effects as an oral agent, Bales added. Mentholated ointments are a safer alternative to decongestants.

“If men notice problems with urination after taking certain medicines, they may need to weigh the risks and benefits,” Dr. Dan R. Gralnek, a urologist with the University of Wisconsin School of Medicine and Public Health, told Reuters Health. Nearly 15 percent of his patients have complications associated with BPH.

Dr. Matthew Johnson, a urologist with Aurora Health Care in Milwaukee, Wisconsin, urges men to carefully read over-the-counter drug labels.

“You have to be aware of what a medication’s potential side-effects are. Unfortunately, the package insert for most medications is quite lengthy,” he told Reuters Health. “Men need to have a relationship with a provider who can monitor these things and individualize their care.”