Q. You wrote recently about the dangers of taking melatonin for insomnia, especially in large doses. In the study you cited, more people taking this pill had heart failure.

The dose might not be quite as high as it seems, though. According to a study of bioavailability, the amount of melatonin actually absorbed by the body is only about 3% (BMC Pharmacology & Toxicology, Feb. 19, 2016). In that light, the large oral tablet doses are not quite as scary as you implied.

People take melatonin because they have difficulty sleeping. Those who don’t sleep well are at significantly higher risk of heart attacks or death. That alone might explain the higher rates of heart failure among people taking melatonin.

A. Thank you for highlighting the study of oral melatonin bioavailability. We didn’t appreciate that only a small amount of melatonin is absorbed from a pill.

The research you cited shows that there is tremendous variability from one person to another. The authors report that prior studies found absorption between 9% and 33%.

A common dosing regimen is 3 milligrams of melatonin taken about one hour before bedtime. If people only absorb 3%, that equals a dose of 90 micrograms, roughly three times more than our bodies normally make in a day.

To learn more about melatonin and other ways to overcome insomnia, you may wish to read our “eGuide to Getting a Good Night’s Sleep.” This online resource can be found under the Health eGuides tab at www.PeoplesPharmacy.com

Q. I started taking Rybelsus early last year to help control Type 2 diabetes. In addition to blood sugar control, this pill helped me lose 50 pounds.

I know Rybelsus is the same medicine as Ozempic and Wegovy. Ozempic can cause gastroparesis. Can Rybelsus also cause this?

A. Gastroparesis means stomach paralysis. The drug semaglutide (Ozempic, Rybelsus, Wegovy) can cause delayed stomach emptying. Symptoms may include abdominal discomfort, a sense of fullness or bloating, nausea, vomiting or indigestion.

The Food and Drug Administration has approved Rybelsus only for treating Type 2 diabetes. But a study in the New England Journal of Medicine (Sept. 18, 2025) reveals that oral semaglutide can also help people lose weight. About one-third of the participants taking the drug lost about 20% of their body weight.

The Novo Nordisk drug company is reported to have applied to the FDA for approval to market an oral form of semaglutide for weight loss. It may be called Wegovy, like the injectable form of this medicine.

Q. Because I like grapefruit, my doctor prescribed rosuvastatin (Crestor) instead of a different statin to lower cholesterol. Later, I added 1/4 cup pomegranate juice to my regimen twice a day. Wow! Joint and muscle pain came on suddenly. It hurt.

I stopped Crestor immediately and gradually felt better. My neighbor’s doctor told him pomegranate juice interacts with statins like grapefruit juice does. Who knew?

A. Grapefruit raises blood levels of statin-type cholesterol-lowering medicines such as simvastatin or lovastatin. That could increase the risk for side effects.

Rosuvastatin is not supposed to interact with grapefruit, however. Just the same, there is a case reported in the medical literature of a 48-year-old man who developed a serious complication while taking rosuvastatin with pomegranate juice (American Journal of Cardiology, Sept. 1, 2006). So even though this interaction is not supposed to occur, at least one other person besides you has experienced it.

In their column, Joe and Teresa Graedon answer letters from readers. Write to them in care of King Features, 300 W. 57th Street, 41st Floor, New York, NY 10019, or email them via their website: www.PeoplesPharmacy.com. Their newest book is “Top Screwups Doctors Make and How to Avoid Them.”