DEAR DR. ROACH: When I was quite young, my doctor told me to never get a flu shot because it could kill me. I do not remember the reason behind this statement. I’m in my 70s now and am very concerned about not getting the shot. I had yellow jaundice as a child and don’t know if this had anything to do with the doctor’s statement. Could you please enlighten me on this? — L.M.

ANSWER: The major risk of getting the influenza vaccine is having an allergic reaction. The most severe of these allergic reactions, anaphylaxis, is indeed life-threatening. Nobody with a well-documented history of anaphylaxis to influenza vaccine, regardless of the presumed vaccine component, should get the influenza vaccine again. Unfortunately, it’s not certain that you are allergic, so there is some confusion about the best course for you.

Jaundice (from “jaune,” which is French for “yellow”) is caused by failure of the liver to correctly metabolize bilirubin, a component of bile. Although many kinds of diseases may cause high bilirubin, which can be seen as a yellow discoloration of the eyes and mouth, a childhood bout of jaundice often indicates a viral hepatitis. This hypothesis could be supported by blood testing, even now. However, I don’t think this has anything to do with the reaction to the flu shot.

Influenza vaccines first became available in the 1940s, but vaccine technology dramatically improved in the 1970s and 1980s. If your doctor’s admonition to avoid the flu shot was due to a bad reaction to a vaccine prior to 1977 or so, it is likely (but not 100% certain) that the current vaccine would be safe and well-tolerated for you.

I would recommend discussion with your current physician, and if you choose to get vaccinated, you should be monitored in a setting where you could be treated for an allergic reaction, although I think the likelihood is small.
DEAR DR. ROACH: Is an elliptical glider safe for a person with arthritic knees? — N.M.

ANSWER: Elliptical training machines have much less impact on the knees and therefore are a good choice for many people with painful osteoarthritis of the knees. However, the foot position needs to be properly fit, and some people can exacerbate back pain from these machines due to the twisting movement that is common when exercising. Still, I think it is a reasonable choice for a person with knee but no back problems.

Swimming probably has the least potential for joint pain due to the buoyancy of the water and the minimal external forces on the joints. Swimmers get the benefit of joint movement, which tends to reduce pain from the osteophytes (“bone spurs”) in osteoarthritis. Strong muscles, from any kind of repeated exercise, also improve movement and balance.

Higher impact exercises are better from the standpoint of strong bones, in terms of their ability to reduce the risk of osteoporosis. There is always a tradeoff of benefits in exercise, and thus no one best exercise to recommend. My best advice is to do the exercise you enjoy, that doesn’t cause symptoms, and that you will keep doing.

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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.