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Saturday, April 20, 2019  Spokane, Washington  Est. May 19, 1883
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House Call: When on medications, pay attention to food and drink

By Dr. Bob Riggs, M.D.

A few months ago I wrote about the importance of taking your medication as prescribed to help insure continued good health. Another important factor to pay close attention to is what you eat or drink before, during, and after taking some medications, including over-the-counter medications.

I have several patients who I have had to place on thyroid medication for hypothyroidism (underactive thyroid gland). I counsel them to take their medication in the morning, 60 minutes before breakfast. Food and beverages interfere with the absorption of thyroid medication. Multivitamins and calcium supplements can interfere with absorption too and should be taken at least four hours before or after taking thyroid medication.

If for some reason you cannot take your thyroid medicine without food, then you need to always take it with food so that it is absorbed the same way every day. Your doctor will monitor your thyroid hormone levels and adjust your dose if needed.

Statins, which help control cholesterol levels, are another type of medication that can be affected by food. Grapefruit can increase the absorption of statins. There is not complete agreement as to whether there is a safe amount of grapefruit or its juice you can consume, so it is best to avoid it while you are on any kind of statin. The absorption of medications to treat high blood pressure, like felodipine and nifedipine, can be affected by grapefruit as well.

Any medications that make you sleepy or drowsy can have that effect made worse by consuming alcoholic beverages. Alcohol also increases your risk of liver toxicity when taken with the over-the-counter pain medications acetaminophen, naproxen, and ibuprofen.

If you are on warfarin, an anticoagulant, you need to be careful about vitamin K. It decreases the effectiveness of warfarin. Limit how much liver, broccoli, spinach, kale, cauliflower, Brussels sprouts, and other foods high in vitamin K you eat.

Vitamin C can decrease the effectiveness of phenobarbital and primidone, anticonvulsant medications. Taking vitamin C supplements or consuming a lot of foods rich in vitamin C like oranges, orange juice, cantaloupe, broccoli, and spinach while on these medications may lead to convulsions.

In addition to foods you eat affecting how a medication is absorbed into your body, some medications affect how nutrients are absorbed into your body.

Acid blockers for heartburn and gastroesophageal reflux disease (GERD) can decrease your absorption of vitamin B12. If you need to be on a medication such as ranitidine, cimetidine, famotidine, or nizatidine for an extended period of time, be sure to eat a balanced diet that includes foods rich in vitamin B12 like eggs, milk, cheese, and fish. You can also discuss B12 supplements with your health care provider.

The cholesterol-lowering medications cholestyramine and colestipol interfere with the absorption of fat-soluble vitamins like A, D, E, and K. Eating foods rich in these nutrients—for instance leafy green vegetables (A and K), salmon (D), and nuts (E)—is important when on these medications.

Diuretics such as furosemide and hydrochlorothiazide can increase mineral loss and laxatives can decrease nutrient absorption. You should include lots of fresh fruits and vegetables in your diet when taking these medications and consult your health care provider if you are considering taking vitamin supplements.

Whether you are taking a medication long-term or short-term, be sure to ask your health care provider or pharmacist if there are any food/drug or drug/nutrient interactions that you should be aware of so that you get the most beneficial effects from your medicine.

Dr. Bob Riggs is a family medicine physician practicing at Group Health’s Riverfront Medical Center.

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