People’s Pharmacy: Can toothpaste contribute to canker sores?

Q. My father and I have both suffered with canker sores all our lives. I’ve heard of eating kiwi fruit to speed healing, and in a recent column, you wrote about sauerkraut.

A few years ago, a dental hygienist told me that canker sores are caused by sensitivity to sodium lauryl sulfate, a foaming agent present in many but not all toothpastes. Since I changed toothpastes, I have dramatically fewer canker sores. Even when I bite the inside of my mouth, the sore spot clears within a day instead of the two weeks it used to take. SLS-free toothpaste has made my life more pleasant.

A. You are not the only reader who has told us that avoiding sodium lauryl sulfate (SLS) reduces the likelihood of canker sores. There is surprisingly little research addressing this topic, given that so many products contain this foaming agent.

One systematic review in the Journal of Oral Pathology & Medicine (May 2019) of the medical literature concluded that use of SLS-free toothpastes helped control aphthous ulcers (canker sores).

Q. What’s your assessment of the value of lithium to prevent dementia?

A. There have long been hints that lithium might be valuable to reduce the risk for dementia (Progress in Neuro-Psychopharmacology & Biological Psychiatry, Aug. 30, 2006). However, most research has focused on anti-amyloid drugs such as aducanumab (Aduhelm) or lecanemab (Leqembi). A systematic review turned up a number of animal studies but only a few clinical trials of lithium for preventing dementia (Ageing Research Reviews, March 2024).

Doses studied vary widely. When lithium is prescribed for bipolar disorder, doses range from 600 to 1,800 milligrams daily. Adverse effects may include diarrhea, muscle weakness, drowsiness, changes in thyroid function and kidney damage.

Much lower doses (10 to 20 milligrams of lithium orotate or citrate) have been used experimentally against depression and dementia. The risks may be reduced at such doses. Much more research is needed on this possible treatment.

Q. I am aware that OTC pain relievers have side effects. However, two different orthopedic surgeons and a sports medicine doctor have all downplayed the risk of ibuprofen and/or naproxen. They recommend that I take one or the other daily for pain and swelling in my knee or hip.

The sports medicine doctor was openly hostile when I said I wouldn’t take ibuprofen as often as he recommended because I am concerned about the health of my kidneys. My two older siblings, who both have had knee replacements, have been advised by their primary care physicians that they can no longer take ANY ibuprofen because of reduced kidney function. Another sibling who worked at a kidney center saw first-hand the horrible things that happen when your kidneys give out for any reason.

I imagine it is hard for doctors that they don’t really have any safe and effective options to offer their patients in pain.

A. You have identified the Achilles heel of anti-inflammatory pain relievers. In addition to damaging the digestive tract, chronic use of drugs like ibuprofen and naproxen can be hard on the kidneys. There is also a risk of elevated blood pressure and cardiovascular complications.

Sometimes natural remedies can be easier on the body. We describe a number of herbal approaches in our “eGuide to Alternatives for Arthritis.” This online resource can be found under the Health eGuides tab at www.PeoplesPharmacy.com.

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.”