Is It Safe To Take Probiotics With Synthroid?
In our latest question and answer, the pharmacist discusses taking probiotics with the thyroid replacement medication Synthroid.
I am currently on Synthroid, which I take first thing in the morning. I have also started taking Phillips Colon Health probiotics for constipation. Can I take the probiotics an hour after the Synthroid when I eat breakfast, or will that impair the absorption of the Synthroid (as I know many supplements do)? Thanks.
Sep 16, 2022- Probiotics can be safely taken with Synthroid as long as you wait at least 30 to 60 minutes after taking your Synthroid before taking the probiotic.
- Taking Synthroid by itself allows it to absorb properly, and separating it from probiotics helps ensure your thyroid medication works as intended.
- Studies show that probiotics taken at least 2 hours after Synthroid do not interfere with thyroid hormone levels.
Answer
Probiotic supplements should be safe to take the same day as Synthroid (levothyroxine). However, they should be taken at least 30 to 60 minutes after taking Synthroid to avoid negatively affecting the absorption of the drug.
The prescribing information for Synthroid, as well as most studies, recommend taking the drug by itself at least 30 to 60 minutes before food or other medications to allow it to absorb consistently.
Taking it with other drugs or food can decrease absorption, potentially making the medication less effective, which could lead to symptoms of hypothyroidism (e.g. lethargy, weight gain, feeling of cold, etc.).
It is even recommended to separate some drugs by more than 60 minutes. These include:
- Fiber supplements
- Antacids
- Calcium supplements
- Magnesium supplements
All of the above are recommended to be separated from Synthroid by at least four hours.
There have been no studies evaluating how probiotics could potentially affect Synthroid absorption if taken at the same time.
However, one study was completed where a probiotic supplement (VSL#3) was taken at least 2 hours after Synthroid. The study showed that, when compared to individuals that did not take the probiotic, there was no difference in thyroid-stimulating hormone (TSH), fT3 (free triiodothyronine), and fT4 (free tetraiodothyronine) levels.
So, as long as you separate your probiotic supplement from Synthroid by the appropriate amount of time (at least 30 to 60 minutes), you should be safe (although it should be noted that some studies suggest that our intestinal bacteria flora can affect thyroid hormone levels in general).
Final Words
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References & sources
- Synthroid Prescribing Information — Abbvie
- Clinical relevancy of the levothyroxine-continuous enteral nutrition interaction — PubMed
- Conditions and drugs interfering with thyroxine absorption — PubMed
- Probiotics Ingestion Does Not Directly Affect Thyroid Hormonal Parameters in Hypothyroid Patients on Levothyroxine Treatment — PubMed
- Link between hypothyroidism and small intestinal bacterial overgrowth — PubMed
Glossary — Terms in This Answer
- Synthroid
- A brand name medication containing levothyroxine, a synthetic thyroid hormone used to treat hypothyroidism.
- Absorption
- The process by which a medication passes through the digestive system and enters the bloodstream.
- Hypothyroidism
- A condition where the thyroid gland does not produce enough thyroid hormone, leading to symptoms like fatigue and weight gain.
- Probiotics
- Supplements containing beneficial live bacteria intended to support digestive and overall health.
- TSH
- Thyroid-stimulating hormone, a blood test measurement that indicates how well the thyroid is functioning.
- FT4
- Free tetraiodothyronine, a form of thyroid hormone circulating freely in the blood that indicates thyroid hormone levels.
- Intestinal bacteria flora
- The community of microorganisms living in the digestive tract that can influence various bodily functions including hormone processing.
Dr. Brian Staiger, PharmD
Doctor of Pharmacy, board certified clinical pharmacist (BCPS), American Herbalist Guild, Medication Therapy Management certified
Brian Staiger, PharmD, BCPS, is a licensed pharmacist with more than 13 years of experience across retail pharmacy, clinical pharmacy, medication safety, pharmacy program development, and healthcare administration. He is the founder of HelloPharmacist.com, where he helps patients...
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