>Q. I know that grapefruit juice is a problem with my blood pressure pill felodipine. I wonder about other juices, like apple and orange juice. Will they affect this or my allergy medication fexofenadine? It is so hard to tell what is safe to eat or drink with your medicine.
A. Grapefruit juice can indeed cause problems with many medications, including felodipine (Plendil), simvastatin (Zocor) and atorvastatin (Lipitor). Blood levels can rise, and that may cause unanticipated side effects.
Other fruit juices may have the opposite effect on certain medications. Fexofenadine (Allegra) is an allergy medicine that might not work very well if taken with apple, orange or grapefruit juice. Such juices may dramatically reduce the absorption of fexofenadine. This could mean there is not enough medicine to relieve allergy symptoms for some people (Pharmacogenetics and Genomics, February 2011).
Many people get in the habit of taking their medicine with juice. It is probably a better idea to take pills with water. This is especially true for antibiotics, blood pressure medicine and drugs to prevent organ-transplant rejection.
>Q. I have been on thyroid medication for the past year. Last fall, I noticed my hypothyroid symptoms returning: fatigue, muscle cramps and stiffness after walking just a mile of my usual three-mile walk. I also felt extremely cold, while others were comfortable.
When I saw my doctor and told him about my symptoms, he checked my thyroid levels and gave me a month's supply of Synthroid to tide me over. I had been taking generic levothyroxine.
A measure of thyroid function, my TSH level, was 3.7 on the generic. On Synthroid, my TSH was 2.5, and all my symptoms disappeared even though the dosage is the same (50 micrograms). If there is such a difference from one brand to another, how can dosage be regulated properly?
A. The Food and Drug Administration maintains that levothyroxine formulations (Levoxyl, Synthroid, etc.) are identical. Physicians who specialize in treating thyroid disorders (The Endocrine Society) disagree. They worry that patients are put at risk when they are switched between brands or generics.
People who get switched need thyroid-function tests afterward. Doses also may need to be adjusted for seasonal variation (lower TSH during the summer).
>Q. I have found a very helpful use for Burt's Bees peppermint lip balm. My nose got really sore the last time I had a cold. Applying the lip balm to my nose and upper lip gave me instant relief. My nose healed within a couple of days.
A. Burt's Bees Lip Balm has a beeswax base with no petroleum products. So far as we know, this type of short-term use should not pose any hazards.
We usually discourage people from using products with a petroleum jelly base in or near the nose, because we are concerned that inhalation of petrolatum might lead to lung inflammation in susceptible individuals.