DEAR DR. DONOHUE: I am writing about a reply you made to an older woman who had scabies. You mentioned permethrin as a treatment. You should recheck your information. The fine print states that it is ineffective for people 65 years of age and older.

Is there any other medicine available to older people that is effective for scabies? – S.A.

ANSWER: The woman to whom you refer was in her 80s, and she wanted information on treatments for scabies. I did recheck this information. One paragraph of the manufacturer’s description of the medicines says “Clinical studies did not identify sufficient numbers of subjects age 65 and over to allow a definitive statement regarding whether elderly subjects respond differently from younger subjects. Other reported clinical experience has not reported differences in responses between the elderly and younger patients.” I questioned dermatologists about this, and they all said they prescribe it for older people. I am so impressed with the effectiveness of permethrin that I get suspicious about the diagnosis when it doesn’t work, even though there are instances when it doesn’t. Brand names for permethrin include Elimite, Acticin and Nix Creme Rinse.

If you have not met with success in using it, other available medicines include lindane (lotion and shampoo), ivermectin (tablets) and 6 percent sulfur in petrolatum or cold cream. A pharmacist has to compound the sulfur mixture. It is messy, has an unpleasant odor and can stain clothes and dry the skin. It’s not a popular remedy.

DEAR DR. DONOHUE: Would you please explain the disease Friedreich’s ataxia? – A.R.

ANSWER: “Ataxia” is a word borrowed from Greek, and it means incoordination. It often is used when a person’s gait is unsteady and causes him or her to fall. It can also cause difficulty speaking, and it might affect the coordination of hand movements. The causes of ataxia are many.

Friedreich’s ataxia is an inherited condition in which signs usually make their appearance before age 25. A staggering walk is a prominent sign. The trunk might shake. Foot deformities like an exceedingly high arch are common. Sensations might be lost. The spine often curves to one side. The illness damages the spinal cord and nerves. Affected people usually end up needing a wheelchair.

One of the most serious complications of this illness is cardiomyopathy, a disruption of heart muscle.

There is no cure.

DEAR DR. DONOHUE: I have been diagnosed with osteoporosis and advised to take Forteo injections. What would be your advice? Are there any side effects to this drug? – A.L.

ANSWER: Forteo is a carbon copy of parathyroid hormone, the product of four small parathyroid glands in the lower neck. That hormone facilitates calcium’s penetration into bone and strengthens osteoporotic bones.

There are side effects to every single drug. Most people tolerate Forteo well. A few complain of dizziness, leg cramps, joint pain or nausea. The medicine is generally used only for two years.

One of the warnings on the drug information alarms many people. It says that osteosarcoma – bone cancer – has occurred in lab animals given three to six times the human dose. No cases have been reported in humans.

There are other osteoporosis medicines. Fosamax and Actonel are tablets that can be taken only once a week, and a newer medicine, Boniva, needs to be taken only once a month.

You have substitutes if Forteo doesn’t work for you.

DEAR DR. DONOHUE: In today’s paper, a woman wrote that she had essential tremor. I am 84 years old, and I also have it. My doctor recommended primidone, and it has worked beautifully for me. – K.A.

ANSWER: Essential tremor – also called familial tremor because it runs in families – most often affects the hands. It comes on when people are making purposeful movements, like trying to bring a cup of coffee to the mouth. It’s a common tremor, and it can make life miserable.

Primidone (band name Mysoline) is a seizure-control medicine that has been found to be quite effective for people with essential tremor. Another popular medicine is the beta blocker propranolol, whose brand name is Inderal.

Dr. Donohue regrets that he is unable to answer individual letters, but he will incorporate them in his column whenever possible. Readers may write him or request an order form of available health newsletters at P.O. Box 536475, Orlando, FL 32853-6475. Readers may also order health newsletters from www.rbmamall.com.