People’s Pharmacy: Is there science to support Vicks VapoRub on feet?

Q. You have written that putting Vicks VapoRub on the soles of the feet can stop a nighttime cough. That’s pure fluff or maybe written as an ad for Vicks. You haven’t bothered to provide any scientific information to support this claim.

A. You are right that there have been no randomized controlled trials of putting Vicks VapoRub on the soles of the feet. Given the distinctive aroma of Vicks, we can’t imagine how you would find an appropriate placebo to conduct such a study.

You are not the only one to dismiss this home remedy. But we have received hundreds of testimonials from people who have found it helpful.

How might it work? One study published in the journal Drugs in Context (Oct. 11) identified the transient receptor potential channel TRPV4 as contributing to acute cough associated with rhinovirus infection. The scientists confirmed that certain ingredients (specifically menthol, camphor and eucalyptus oil found in Vicks) activate TRPV4 as well as TRPV1 and TRPM8. They suggest that this activation could help reduce cough symptoms.

So, what’s a TRP channel and what are they doing on the feet? These channels modulate the passage of ions into cells, and they are found throughout the digestive tract as well as in the skin (Pharmaceuticals, Dec. 14, 2016). Nerves in the skin that detect temperature have generous supplies of TRP channels.

Most over-the-counter cough and cold remedies contain the oral decongestant phenylephrine, which the Food and Drug Administration recently admitted is ineffective. Questions have also been raised about the safety and effectiveness of dextromethorphan (DM), the ingredient in most over-the-counter cough suppressants (Journal of Pharmacy and Pharmacology, September 2000).

We take no money from drug companies to promote their products. This is not an “ad for Vicks.”

Q. I am on Synthroid for hypothyroidism. About a year ago, my doctor lowered the dosage. After six months on the lower dose, my hair started falling out like crazy. My hairdresser even found a few areas with no hair! To counteract this, I started using a shampoo containing biotin. I am convinced that the biotin has helped me to regrow my hair.

A. Levothyroxine (Synthroid) is the primary treatment for hypothyroidism, a condition in which the thyroid gland produces too little of this essential hormone. When thyroid levels are too low, people frequently experience hair loss (Medicine, Jan. 5). Sudden hair loss of the type you describe is known as telogen effluvium.

Unfortunately, the remedy you have chosen may pose a problem. Biotin from shampoo could be absorbed through the skin (Journal of Nutrition Science and Vitaminology, June 1999). Biotin can interfere with thyroid tests, lowering TSH and raising T4 and T3 levels falsely (Annals of Clinical and Laboratory Science, January 2023). As a result, your doctor might conclude your thyroid dose is working better than it actually is. And that could lead to more hair loss. If you stop using biotin several days before your next blood test, you should get accurate test results.

You may want to consult our “eGuide to Thyroid Hormones” for more information on testing for hypothyroidism, as well as drugs and supplements that can affect test results and natural hormones.

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, Fla., 32803, or email them via their website: www.PeoplesPharmacy.com. Their newest book is “Top Screwups Doctors Make and How to Avoid Them.”