Q. In my state, marijuana use is illegal. I started using CBD products to treat nerve pain after a shingles attack. I’m not sure that it worked all that well, but the CBD helped me get through until a neurologist could figure out a treatment program.

The problem is that I tested positive for marijuana even though I was only using CBD. How could that happen?

A. CBD is short for cannabidiol, a compound found in Cannabis sativa, the Latin name for marijuana. CBD does not make people high like another marijuana compound, tetrahydrocannabinol (THC). Despite this, some CBD products may contain enough THC or other cannabinoids to set off alarms on a drug test. It’s impossible to say whether this is due to inherent biological variability in the source plants or contamination during processing.

In theory, CBD has nothing to do with THC. But as Yogi Berra has been quoted: “In theory, there is no difference between practice and theory. In practice, there is.”

Q. About a month ago, someone wrote to you that Neosporin cleared up their toenail fungus in short order. I’ve been on prescription ciclopirox for three years without results. I tried Neosporin ointment for a month and got absolutely no help.

You need to fully investigate these claims by people. If they don’t work, print a retraction!

A. We understand your frustration, but even the most powerful Food and Drug Administration-approved prescription drugs to treat nail fungus don’t work all the time. And they usually take up to a year for a complete cure.

So-called nail fungus is not always caused by a fungal infection. A study published in the Journal of the American Podiatric Medical Association (March 1, 2021) revealed that many cases are mixtures of bacteria and fungi, and a minority is caused by fungus alone.

Topical medicines like ciclopirox have a cure rate of less than 12% after almost a year. That’s not very impressive.

The reader who got good results with Neosporin used it on the recommendation of a podiatrist who had tested the nails. Those nails were infected with bacteria.

Q. I have suffered from nighttime reflux for as long as I can remember. I relied on Tums before bed until I developed kidney stones. The doctor said the extra calcium was a contributing factor.

I switched to omeprazole, but the label said to take it for only two weeks. When I stop, my heartburn comes back. What else can I do?

A. Cutting back on carbs, especially in the evening, could be helpful (Digestive Diseases and Sciences, August 2006). If you like home remedies, this reader has an approach you might like:

“My husband finely chews and then swallows a bout six almonds before bed each night. Before he started this practice, he had terrible heartburn. Since then, he hasn’t had any heartburn unless he forgets his almonds.”

You can learn more about these and many other options for managing heartburn in our eGuide to Overcoming Digestive Disorders. This online resource may be found under the Health eGuides tab at www.PeoplesPharmacy.com.

Too much calcium from antacids containing calcium carbonate could increase the risk for kidney stones (Annals of Internal Medicine, April 1, 1997). Calcium-rich food does not seem to pose this problem, however.

In their column, Joe and Teresa Graedon answer letters from readers. Write to them in care of King Features, 628 Virginia Drive, Orlando, FL 32803, or email them via their website: www.PeoplesPharmacy.com.

— King Features