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The People’s Pharmacy: Why does soap under the sheets lose its power?

Q. I have used soap under the sheets and found that it helps prevent muscle cramps. I read in your column that the effect wears off after several weeks. Why? Since it isn’t being used for bathing, why would it wear out?

A. There is relatively little scientific study of the anti-cramping effect of soap under the sheets. One theory, however, is that it works by releasing volatile chemicals such as limonene, a natural compound found in the rinds of lemons, limes and oranges. These agents are added to soap for their aroma.

An anesthesiologist who was intrigued by the reports of soap fighting cramps tested crushed soap against muscle cramps and menstrual cramps (Journal of Alternative and Complementary Medicine, July 2008). He proceeded to test the scent alone and reported that it relieved muscular pain (Journal of Multidisciplinary Healthcare, September 2008).

The soap releases its fragrance compounds slowly over time. Eventually their concentration diminishes, which may explain why some people report that the soap loses its effectiveness after a few months.


Q. I’ve had a sore, irritated tongue for months. I first went to my primary-care doctor and then to an ENT doctor. The ENT doctor prescribed “Magic Mouthwash,” which was not covered by my prescription plan. I contacted my primary-care doctor again, and she said to stop taking goldenseal. She thought the herb was irritating my tongue. She was right!

A. Goldenseal (Hydrastis canadensis) is popular this time of year for boosting the immune system. It is even found in mouthwashes. Some people gargle with such “natural” products to relieve sore throats.

One of the adverse effects of goldenseal, however, is that it can irritate the mouth and throat. It also can make skin more sensitive to sunburn.


Q. This winter I find that I have a hard time getting out of bed. My energy level is very low, and I’ve gained weight. My doctor said I am depressed and prescribed an antidepressant. I don’t feel any better while taking it, though.

My only other medication is levothyroxine for hypothyroidism. Could there be an interaction between levothyroxine and sertraline?

A. Sertraline, like some other antidepressants, can occasionally disrupt thyroid function. You may be caught in a vicious cycle in which sertraline reduces thyroid activity and reduced thyroid activity makes you feel depressed.

During the winter, some people need more thyroid hormone than during other seasons (Journal of Clinical Endocrinology and Metabolism, June 1982).

Low thyroid activity can lead to symptoms of depression and lack of energy along with many other health problems, such as weight gain. Our 25-page Guide to Thyroid Hormones explains drug interactions, symptoms, testing and treatment in far greater detail. It can be downloaded for $3.99 from


Q. I read your article in my paper titled “Beets may boost benefits from Viagra.” I’d love to try it. However, nothing was mentioned about how much beet juice to take and how long one should take it before having sex. Any suggestions?

A. The woman who wrote to us about her husband’s use of beet juice to enhance the effect of sildenafil (Viagra) implied that eating beets or drinking a glass (6 to 8 ounces) of beet juice the day prior to sexual activity would improve the effectiveness of the drug. Blood pressure may drop, however, so caution is appropriate.

The People’s Pharmacy radio broadcast airs at 2 p.m. Saturdays on WBFO-FM 88.7.