Hypothyroidism indicates a problem with your thyroid gland. This small, butterfly shaped gland has two lobes that sit on either side of your windpipe. It performs several functions, including maintaining the proper balance of calcium in your body and the secretion of hormones to regulate your metabolism. Taking Alli, a weight loss medication, while on hypothyroid medication can cause an adverse reaction. If you have hypothyroidism, consult your doctor before taking Alli.
Hypothroidism
A hypothyroid diagnosis means you have an underactive thyroid that produces an insufficient amount of hormones for your body to function properly. Causes of hypothyroidism include birth defects, radiation treatments for neck cancers, and radioactive iodine treatment for hyperthyroidism -- an overactive thyroid gland. You can also develop hypothyroidism from prescription medication, including lithium and methimazole, a drug used to treat hyperthyroidism. The most common treatment for hypothyroidism is hormone replacement therapy with the drug levothyroxine, according to information from Medline Plus.
Alli
The weight loss medication Alli is the over-the-counter version of the drug orlistat. Alli prevents your body from absorbing fats from food; some people refer to Alli as a fat blocker. Orlistat binds to fat in the food you eat and escorts it through your digestive system undigested, so you don't gain weight. The Food and Drug Administration regards Alli as a viable treatment for weight loss, but this medication works best when combined with a reduced calorie diet and regular exercise.
Levothyroxine
Doctors prescribe levothyroxine, a synthetic thyroid hormone, for hypothyroidism. This medication controls, but does not cure, hypothyroidism, and it may take a few weeks until you notice an improvement in your symptoms. Taking Alli with levothyroxine may interfere with your body's ability to absorb the thyroid hormone properly, rendering it less effective, according to information from Drugs.com. It suggests taking these two medications at least four hours apart, but only under close supervision of your physician.
Risk of Interaction
Drugs.com rates the interaction between levothyroxine and Alli as moderate. This means the negative interaction is clinically significant and patients should usually avoid combining these medications, except under special circumstances. Symptoms resulting from this interaction include but are not limited to muscle pain, hair loss and intolerance to cold as well as menstrual irregularities, weight gain and joint stiffness. Consult with your doctor if you experience these symptoms, and only take the two together under your physician's supervision.
