Synthroid With Glucosamine - Chondroitin

In our latest question and answer, the pharmacist discusses the use of Synthroid with glucosamine/chondroitin supplements.


I'd like to start taking glucosamine (Osteo Bi-Flex), but I am on Synthroid. I know a lot of drugs interact with Synthroid absorption so I thought I'd ask a few questions. Is there any interaction between glucosamine/chondroitin and Synthroid? Can I take glucosamine/chondroitin and Synthroid at the SAME TIME? If I can't take at the same time, how long do I have to wait? How much glucosamine/chondroitin should I be taking daily? Any brand recommendations? Is the once a day pills too strong?

Asked by Mike On May 06, 2019

Answered by
Medical Content Reviewed By PharmacistAnswers Staff

On May 07, 2019
White capsule with powder spilling out with Synthroid glucosamine text


There is no drug-drug interaction between Synthroid and glucosamine/chondroitin, but you should separate the dosing of them by at least 30 to 60 minutes to avoid any interference with Synthroid absorption.

Synthroid is generally recommended to taken first thing in the morning, 30 to 60 minutes before eating or drinking (except for water).

Taking Synthroid along with other drugs, food or beverages besides water can significantly decrease absorption of the drug, potentially reducing effectiveness.[1]

How To Take Synthroid

The prescribing information for Synthroid states the following regarding how the drug should be taken:[2]

Administer SYNTHROID as a single daily dose, on an empty stomach, one-half to one hour before breakfast. Administer SYNTHROID at least 4 hours before or after drugs known to interfere with SYNTHROID absorption

Food and other drugs are well known to cause decreases in Synthroid absorption.

Even if a given drug doesn't necessarily have an 'interaction' with Synthroid in terms of altering its effects, most will at least decrease total absorption which could potentially lead to you not getting your intended dose.

This, of course, could lead to symptoms of hypothyroidism.

Therefore, as a general rule of thumb, it is important to take Synthroid the same way every day, which is preferably in the morning on an empty stomach for optimal effects.

Questions Answered

Below, I answer each of your questions specifically.

Is there any interaction between glucosamine/chondroitin and Synthroid?

As described above, taking any drug or food with Synthroid can decrease the absorption of it. Therefore, Synthroid should be taken by itself.

Can I take glucosamine/chondroitin and Synthroid at the SAME TIME?

No, you shouldn't take them at the same time since Synthroid absorption can be negatively affected.

If I can't take at the same time, how long do I have to wait?

Synthroid should be taken first, and glucosamine/chondroitin can be taken 30 to 60 minutes later.

How much glucosamine/chondroitin should I be taking daily? Any brand recommendations? Is the once a day pill too strong?

There are no established dosage guidelines for glucosamine and chondroitin supplements, unfortunately.

Most studies show mixed results in regard to how well it works and the American College of Rheumatology neither recommends it nor gives dosage guidance in those who want to try it.[3]

Nevertheless, there are some studies that have reported positive results.

One such study, published in the New England Journal of Medicine, did find it reduced pain in some patients with moderate to severe knee osteoarthritis. Clearly, more studies are needed to fully elucidate the potential benefits of glucosamine/chondroitin supplements.[4]

Supplements range in regard to dosages, but the most common range is between 400 to 800 mg chondroitin with 500 to 1,000 mg glucosamine, and are recommended to be taken 2 to 3 times per day.[5]

I don't recommend any specific brand, but you certainly want to go with an established brand name you trust and has a good history of safety and manufacturing practices.

As long as you tolerate a once-daily pill, there are no studies to suggest that they are any more or less effective.


Synthroid should be taken by itself, in the morning on an empty stomach. It should be taken at least 30 to 60 minutes before glucosamine/chondroitin supplements to avoid any interference in absorption.

  1. ^ Elsevier ClinicalKey: Synthroid Monograph. ClinicalKey
  2. ^ Synthroid Prescribing Information. RxAbbvie
  3. ^ A systematic review of recommendations and guidelines for the management of osteoarthritis: The chronic osteoarthritis management initiative of the U.S. bone and joint initiative. PubMed
  4. ^ Glucosamine, chondroitin sulfate, and the two in combination for painful knee osteoarthritis. PubMed
  5. ^ Natural Standard: Glucosamine Monograph. Natural Standard

About the Pharmacist

Dr. Brian Staiger Pharm.D

Dr. Brian Staiger is a licensed pharmacist in New York State and the founder of He graduated from the University At Buffalo with a Doctor of Pharmacy degree in 2010. He has been featured in numerous publications including the Huffington Post as well as a variety of health and pharmacy-related blogs. Please feel free to reach out to him directly if you have any inquiries or want to connect! He's answered thousands of medication and pharmacy-related questions and he's ready to answer yours! Office: 716-389-3076

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