Can You Take Levothyroxine And Iron Supplements Together?
In our latest question and answer, the pharmacist discusses the interaction between levothyroxine and iron.
My doctor gave me a prescription to Ferrous Gluconate and Levothyroxine. I take 2 pills every other morning for Ferrous Gluconate. I take 1 pill every morning for levothyroxine. I read that they aren't supposed to be taken together. How should I take them?
May 24, 2023- Iron supplements can interfere with how your body absorbs levothyroxine, which may reduce the medication's effectiveness in managing your thyroid condition. You should take levothyroxine and iron supplements at least 4 hours apart to ensure both work properly. Taking levothyroxine first thing in the morning on an empty stomach, separated from food and other medications by 30-60 minutes, provides the best absorption.
Answer
Thanks for reaching out! I can certainly provide you with information regarding the interaction between ferrous gluconate and levothyroxine, and how to properly take these medications.
Interaction Detail
Ferrous Gluconate is a supplement that contains iron, while levothyroxine is a medication used to treat thyroid conditions.
Iron supplements, such as ferrous Gluconate, can interfere with the absorption of levothyroxine in the body and therefore, taking them together may reduce the effectiveness of the levothyroxine. This could negatively affect your thyroid levels.
Specifically, the iron ions in ferrous gluconate can bind to levothyroxine in the gastrointestinal tract, forming complexes that are poorly absorbed by the body. As a result, the bioavailability (rate and extent of absorption) of levothyroxine may be significantly reduced.
Levothyroxine requires optimal absorption to effectively regulate thyroid hormone levels in the body. When its absorption is compromised, there is a risk of inadequate thyroid hormone replacement, which can impact the management of thyroid conditions.
To ensure optimal absorption and effectiveness of your levothyroxine, it is recommended to separate the administration of these medications.
According to the prescribing information for Synthroid (a brand name for levothyroxine), it is advised to avoid taking levothyroxine tablets within 4 hours of iron and calcium supplements, as well as antacids. The prescribing information states this:
Inform patients that agents such as iron and calcium supplements and antacids can decrease the absorption of levothyroxine. Instruct patients not to take SYNTHROID [levothyroxine] tablets within 4 hours of these agents.
Additional Information
In general, levothyroxine is recommended to be taken by itself, first thing in the morning, separated by food and other medications by at least 30-60 minutes for optimal absorption. Some medications/supplements, like iron, should be separated by longer periods of time (4 hours as mentioned in the section above).
Making things a little tricky here is that iron supplements are also often recommended to be taken on an empty stomach for optimal absorption.
If you are going to be taking levothyroxine and iron on the same day, it would be best to try to work out a schedule where you can take both on an empty stomach, while separating them from each other by 4 or more hours.
Final Words
I hope this answer helped! Let me know if there is anything else I can answer for you.
References & sources
- Synthroid Prescribing Information — AccessFDA
Glossary — Terms in This Answer
- Ferrous gluconate
- A form of iron supplement used to treat or prevent iron deficiency in the body.
- Levothyroxine
- A synthetic thyroid hormone medication used to treat an underactive thyroid gland.
- Absorption
- The process by which a medication or nutrient enters the bloodstream from the digestive system.
- Gastrointestinal tract
- The digestive system including the stomach and intestines where food and medications are broken down and absorbed.
- Bioavailability
- The amount and rate at which a medication is absorbed into the bloodstream and becomes available to work in the body.
- Thyroid hormone
- A chemical substance produced by the thyroid gland that helps regulate metabolism and body functions.
- Antacids
- Medications used to neutralize stomach acid and relieve heartburn or indigestion.
- Empty stomach
- A state where no food or other substances have been consumed for several hours before taking medication.
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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