DEAR DR. ROACH: I have scleroderma with Raynaud's phenomenon, and friends and family members have told me that I might get help from Viagra.

Frankly, I hadn't read or heard that from either my rheumatologists or dermatologists. I already tried a short course of nifedipine over a decade ago (it just gave me a headache), so I just stick with mechanical means to keep my hands warm in winter and, maybe surprisingly to some, in summer. Believe me, air-conditioned grocery stores are torture from April to October. -- M.A.P.

ANSWER: Raynaud's phenomenon is an excessive response of the blood vessels in the skin to changes in temperature, and sometimes to emotional stress. While most people will get cold hands and feet when it is cold, a person with Raynaud's can get a drastic response, even to air conditioning or freezer sections of grocery stores. The skin will turn white and then blue, then quite red on being rewarmed. Not everybody goes through all three colors, however.

Raynaud's can exist by itself, but is often seen in the presence of autoimmune conditions, such as the systemic sclerosis (scleroderma) you have. Treatment for Raynaud's is generally the same with or without other conditions. Everybody with Raynaud's should quit smoking and avoid medications that can trigger an attack (over-the-counter cold and flu remedies are the most common).

The mainstay of treatment is avoiding the temperature changes wherever possible, but as you point out clearly, it's almost impossible to do so completely. Putting your hand in a refrigerator or holding a cold drink can trigger an attack. Many people with Raynaud's learn to keep gloves with them all the time and dress their entire body warmly. An attack can sometimes be aborted by rubbing hands in warm water or getting them into a warm place.

When medication treatment is necessary, a calcium channel blocker like nifedipine is often the first choice. Headache and dizziness can limit effectiveness of this treatment. Studies have shown these medications can cut the attacks by about 50%.

Sildenafil (Viagra) has been used in people with Raynaud's, and is about as effective as calcium channel blockers. However, for people with scleroderma, ulcers and Raynaud's, sildenafil has been shown in small trials to be very effective.

DEAR DR. ROACH: My wife has many allergies and asthma, as well as frequent migraines, about two or three a month. A family friend has been using Aimovig for the past six months with no migraine symptoms. What can you tell me about this relatively new drug? We're concerned that the side effects may interfere with her asthma, or any other negative drug interactions. -- M.S.

ANSWER: Erenumab (Aimovig) has been recently approved for migraine. In the initial study, it reduced the number of migraine days from 8.3 to 4.6 per month. As an injection, it may cause pain and swelling at the injection site, and has also caused some people constipation and muscle cramps. There are very few drug interactions, and I found no indication that it should make asthma worse.

Your family friend has had a much better result than most of the people in the study, and there is no guarantee your wife will do as well. I am awaiting further long-term studies before recommending this class of migraine treatments.

It is given once per month, and costs about $600 at goodrx.com.

Dr. Roach regrets that he is unable to answer individual letters, but will incorporate them in the column whenever possible. Readers may email questions to ToYourGoodHealth@med.cornell.edu or send mail to 628 Virginia Dr., Orlando, FL 32803.