Levothyroxine & Caffeine

Levothyroxine is one of the most commonly prescribed thyroid medications, used to replace or supplement the hormones a healthy thyroid naturally produces. Caffeine is a widely available substance found in coffee, tea, soft drinks and chocolate. Like many other drugs and medications, caffeine interferes with your body's ability to take up levothyroxine. You can still eat and drink foods containing caffeine as long as you precisely follow your physician's instructions for levothyroxine dosing and avoid taking caffeine at the same time.

The caffeine in coffee can interfere with the absorption of thyroid medication. (Image: Purestock/Purestock/Getty Images)

Levothyroxine

Levothyroxine, also called T4 or thyroid hormone, is sold under such brand names as Synthroid, Levoxyl and Unithroid. Doctors prescribe this drug for patients whose thyroids do not manufacture sufficient amounts of hormone or who have had their thyroids removed due to disease or cancer. The medication is usually taken every day and is generally required for life.

Caffeine

Caffeine is a bitter-tasting substance found in all non-decaffeinated coffees as well as many teas, sports drinks and soft drinks. Caffeine is an ingredient in some pain relief medication, including Maximum Strength Anacin and Extra Strength Excedrin. Chocolate also contains caffeine, although to a much lesser degree. Caffeine stimulates the nervous system and can help you stay alert. Too much caffeine, however, has deleterious effects and can lead to irritability, sleeplessness and abnormal heart rhythms.

Levothyroxine and Caffeine Interaction

A study described in “Clinical Thyroidology for Patients” reported that coffee, if consumed at the same time as or slightly after swallowing levothyroxine, interferes with the proper absorption of levothyroxine. In particular, those patients with little or no natural thyroid function are most likely to suffer the deleterious effects of levothyroxine malabsorption. Since they can produce little if any natural thyroid hormone, their bodies are not able to compensate for decreased amounts of levothyroxine.

Recommendations for Use

You can still drink caffeine-containing beverages if you take levothyroxine, as long as you do not ingest caffeine at the same time as your medication. Your doctor will most likely direct you to take levothyroxine on an empty stomach with a full glass of water and to avoid eating and drinking anything other than water for an hour afterward. To avoid any interaction with caffeine, allow six hours to pass, if possible, between the time you take levothyroxine and the time you drink coffee or another caffeine-containing beverage. To avoid any fluctuations in your day-to-day absorption of levothyroxine, maintain a consistent time schedule for taking both your medication and for ingesting caffeine, suggests “Pharmacy Times.”