Q. I have been feeling very anxious about being stuck at home most of the time because of the coronavirus. Stress has led me to start biting my nails again. My thumbs look awful, and my wife gives me a lot of grief about them.

I have sometimes used instant glue to stop myself from chewing on the rough spots. I figure that it’s not healthy to swallow the dried glue. Do you have any other ideas about how to overcome this horrible habit?

A. Nail-biting is a particularly bad habit when you are trying to avoid infection with COVID-19. No amount of preaching about keeping your hands away from your face (and your fingers out of your eyes, nose and mouth) will give you the willpower to just stop cold turkey. Neither will the impressive name doctors call it: onychophagia.

However, Australian scientists may have come up with a promising aid almost by accident. According to The Wall Street Journal (Dec. 28, 2020), they were testing a nutraceutical, N-acetyl cysteine (NAC), for its ability to help people with bipolar disorder. Unexpectedly, a few of the people in the study stopped biting their nails while they were taking the supplement (CNS Spectrums, Nov. 7, 2014). It may be helpful against other obsessive behaviors such as hair pulling as well.

A randomized controlled trial found that NAC was more effective than placebo in helping youngsters stop biting their nails (Anti-inflammatory & Anti-allergy Agents in Medicinal Chemistry, 2013). The study was small, however. We’d really like to see more research before we become overly enthusiastic. NAC is inexpensive and safe, so you might want to give it a try. Let us know how it works for you.

Q. A few days ago, I got the sniffles and a sore throat. Then I developed a cough. Needless to say, I freaked out thinking I might have caught COVID. Luckily, the test was negative.

I am suffering pretty classic cold symptoms and would like to take something that would enhance my immune system. Are there any natural remedies that I could order online?

A. A surprising number of supplements can help the body resist infection. Vitamin C is controversial, but a recent review concludes that “cold symptoms have been shown to be less severe and resolve more quickly with oral vitamin C with a dose-dependent effect” (Nutrients, Dec. 7, 2020).

Vitamin D is also useful against respiratory infections. The minerals zinc and selenium have well-established antiviral activity (BMJ Nutrition, Prevention, and Health, May 20, 2020).

You may also want to consider botanical medicines such as elderberry, astragalus and Andrographis. All of these have been shown to be helpful for treating coughs and other cold symptoms.

You can learn more about these herbal remedies as well as the nutraceuticals in our eGuide to Colds, Coughs & the Flu. This online resource may be found in the Health eGuides section of our website, www.PeoplesPharmacy.com. In addition, it contains information on how to make Grandma Graedon’s medicinal (and delicious) chicken soup and how to use dark chocolate to calm a cough. It also offers simple instructions on another of our favorite cold remedies, hot ginger tea.

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