Go Ad-Free
logoThe People's Perspective on Medicine

Can GI Problems Interfere With Thyroid Medication?

Q. I have suffered with stomach pain and reflux for a long time. I have tried Zantac and Pepcid without much success. I am now taking Prevacid that my doctor prescribed to control excess acid. Even after an increase in dose I am still experiencing gastrointestinal upset. Any ideas?

I also have a thyroid problem. My endocrinologist started me on Synthroid and recently switched me to Levoxyl. Now I am noticing side effects. It seems as if the drug isn’t working the way it used to. I know these drugs are supposed to be equivalent but my body says something different. Should I ask my doctor to put me back on Synthroid?

A. Substituting one brand of levothyroxine (Levoxyl) for another (Synthroid) may require an adjustment in dose. But first, you and your doctor need to consider your stomach problems.

An article in The New England Journal of Medicine (April 27, 2006) shows that people with low stomach acidity do not absorb levothyroxine well and may need a higher dose. The Prevacid you are taking reduces stomach acid.

People infected with stomach bacteria called Helicobacter pylori also seem to have trouble absorbing thyroid hormone. This bug may also be contributing to your GI problems. We discuss the treatment of this infection in our Guide to Digestive Disorders. Our Guide to Thyroid Hormones has more information on levothyroxine and other drugs that may interact with it.

Rate this article
star-fullstar-emptystar-fullstar-emptystar-fullstar-emptystar-fullstar-emptystar-fullstar-emptystar-fullstar-emptystar-fullstar-emptystar-fullstar-emptystar-fullstar-emptystar-fullstar-empty
4.2- 5 ratings
About the Author
Joe Graedon is a pharmacologist who has dedicated his career to making drug information understandable to consumers. His best-selling book, The People’s Pharmacy, was published in 1976 and led to a syndicated newspaper column, syndicated public radio show and web site. In 2006, Long Island University awarded him an honorary doctorate as “one of the country's leading drug experts for the consumer.”.
Tired of the ads on our website?

Now you can browse our website completely ad-free for just $5 / month. Stay up to date on breaking health news and support our work without the distraction of advertisements.

Browse our website ad-free
Join over 150,000 Subscribers at The People's Pharmacy

We're empowering you to make wise decisions about your own health, by providing you with essential health information about both medical and alternative treatment options.