DEAR DR. ROACH: I am a 62-year-old female in excellent health. I eat right, exercise and have a great genetic history. I have no high blood pressure. For about four years I have been taking two Sudafed pills, 30 mg per tablet, on average every other day, to alleviate morning headaches and congestion. Is there any long-term danger to taking Sudafed like this? — R.R.

ANSWER: Pseudoephedrine is a decongestant. It works by constricting blood vessels, such as those in the nose, making it easier to breathe. However, it constricts blood vessels everywhere, and in some people, especially those with existing high blood pressure, pseudoephedrine can raise the blood pressure to dangerous levels.

Older men have another reason to worry about using Sudafed. The way it works in the body is by activating receptors on the blood vessels, called alpha receptors. These cause the blood vessels to tighten up. Those same receptors exist in a man’s prostate gland. Drugs like Flomax are alpha blockers and are given to relax muscles in the prostate and allow the urine to flow. Urine goes through the urethra, which runs right through the prostate. Sudafed has the opposite effect and can cause the sudden inability to urinate at all, in men with enlarged prostates.

For women and younger men without high blood pressure, occasional Sudafed is safe.