DEAR DR. ROACH: Why didn't you recommend one of the at-home kits for the person with Lynch syndrome who had a bad reaction during her colonoscopy? I don't ever intend to have another colonoscopy. It is invasive, the prep is too much (yes, I understand why), and it takes up 24 hours of your time.

-A.T.

Answer: Lynch syndrome, also called hereditary nonpolyposis colorectal cancer syndrome, is a condition that is caused by a genetic mutation in a DNA mismatch repair gene. Without this mismatch repair system, some cancers are much more likely, especially colon cancer. People with Lynch syndrome are at a much higher risk for colon cancer.

Cologuard and other at-home tests are not intended for and have not been tested in people with Lynch syndrome. Furthermore, people with Lynch syndrome quickly progress from having normal tissue to having cancer and may bypass the DNA sequences that the stool-based tests are designed to detect. Lynch-syndrome cancers are also preferentially on the right side of the colon, which is harder for Cologuard to detect.

People with Lynch syndrome should get a full colonoscopy every one to two years, beginning several years before the youngest family member was diagnosed or between ages 20-25 - whichever is earliest. Cologuard is a good test for people who will not or cannot do a colonoscopy. I continue to get a colonoscopy as it's a more sensitive test.

DEAR DR. ROACH: I take 1 capsule per day of over-the-counter Prevacid for acid reflux. If I do not take 1 capsule per day, I begin to experience reflux symptoms within a day or two.

Prevacid provides me with better symptom control than other proton-pump inhibitors (PPls) and much better control than H2 antagonist meds.

What are the risks of taking 1 PPI capsule daily versus tolerating acid reflux? Does Prevacid pose more or less of a risk than other over-the-counter PPls on the market?

-G.K.

Answer: PPls like omeprazole (Prilosec) and lansoprazole (Prevacid) prevent the stomach cells from making acid. They are very effective in people with severe reflux and can help with healing stomach ulcers. However, they do have some potential side effects.

People who regularly take them are at risk for infections, particularly the serious colon infection Clostridioides difficile. The risk is about 30% higher than for people who don't take them and higher than it is for people who take H2 blockers like famotidine (Pepcid). However, for average-risk people, the risk is small - roughly one person per thousand each year.

PPI users often cannot properly absorb calcium, magnesium and vitamin B12. In my patients who are on long-term PPI treatment, I periodically check their magnesium levels and recommend calcium citrate as well as B12 supplements.

The association of PPI use with pneumonia and dementia is controversial. I recommend that all adults over 50 get the pneumococcal vaccine, but it is particularly important in those who take PPis. I have carefully read the studies on dementia, and at this point, I do not believe that there is a significant risk. However, I do warn patients that this is a possible side effect of long-term PPI use.

Contact Dr. Roach at: ToYourGoodHealth@med.cornell.edu.