Q: I read recently about LipiFlow treatment to provide temporary relief for dry eyes. However, my ophthalmologist quoted the treatment cost at $1,000 per eye.

I am now taking a new prescription medication for dry eyes. Since it is new, the prescription cost is outrageous — $500 for a 30-day supply. It’s called Xiidra. Patients are given a trial supply before purchasing. I’ve found that it works immediately. In comparison, Restasis takes months to make any difference.

A: The Food and Drug Administration approved lifitegrast (Xiidra) last year as the first in a new class of drugs for dry eyes. It works by affecting the immune system to reduce inflammation.

More than 2,000 adults have participated in randomized controlled trials of these eyedrops. Reviewers for The Medical Letter on Drugs and Therapeutics concluded that it is safe and modestly effective (JAMA, April 11, 2017). Side effects of Xiidra include blurred vision, eye irritation, pain, itching and a peculiar taste in the mouth.

The biggest drawback for this new approach is the cost. If insurance companies won’t approve or pay for these eyedrops, most people will find it hard to afford them.

Q: I am a 77-year-old man who has been taking zolpidem (Ambien) for 15 years so I can get the sleep I need. Now, however, I have a new primary care physician who will not renew my prescription because “it is not within the guidelines for those 65 and older.”

I have explained to the doctor that I need this medicine to fall asleep. Moreover, in the 15 years I have taken it, I have never, ever had a side effect. Until just three months ago, I worked a job that required me to wake at 5:40 in the morning, and I still had zero side effects.

My doctor is adamant and has prescribed trazodone, which apparently is within the guidelines. However, I read the warnings that come with the prescription and found that those with kidney disease should not take trazodone. I have stage 3 kidney disease.

Can you suggest another sleep aid that is not hazardous to my remaining kidney?

A: Zolpidem is on the Beers list of drugs that often are inappropriate for older people. We’re not sure that trazodone is safer, however. It is an antidepressant that has never been FDA-approved for insomnia. It can cause next-day drowsiness, dizziness, confusion, dry mouth, blurred vision, unsteadiness and headache.

Phasing off zolpidem to avoid rebound insomnia may take several weeks of gradual dose reduction. Nondrug options include dietary supplements such as melatonin, 5-HTP or tryptophan. There is evidence that tart cherry juice can help people fall asleep more quickly and sleep longer. You can find details on these and other sleep aids in our Guide to Getting a Good Night’s Sleep. This 22-page online resource is available at www.PeoplesPharmacy.com.

Q: If Pepto-Bismol causes black stools, what does it mean? Should I take something else for upset stomach?

A: Pepto-Bismol (bismuth subsalicylate) is a popular medicine for upset stomach and diarrhea. It frequently makes the stool black, but that is expected.

If you had black stool without taking Pepto-Bismol or any other medication with bismuth, you should see your doctor promptly. Black, tarry stools can result from intestinal bleeding.

Usually it is fine to take Pepto-Bismol for a few days, but it should not be taken long term. Too much bismuth can lead to problems. If your digestive difficulties continue for a longer time, they deserve medical attention.

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. Their newest book is “Top Screwups Doctors Make and How to Avoid Them.”