Can You Take Folic Acid With Levothyroxine? Understanding the Relationship and Timing

October 10, 2025 •

3 min read

According to a study published in BMC Endocrine Disorders, a low serum folate level is significantly associated with an increased risk for elevated thyroid-stimulating hormone (TSH) in patients with type 2 diabetes. For those wondering, can you take folic acid with levothyroxine?, the short answer is yes, they can be taken together, but the timing is crucial to ensure both medications are absorbed effectively.

Quick Summary

Taking levothyroxine and folic acid together is safe, but optimal absorption requires separating them by at least four hours. Hypothyroidism can cause low folate levels and high homocysteine, a cardiovascular risk factor. Correct timing ensures levothyroxine efficacy, while supplementation can address related deficiencies.

Key Points

No direct interaction: Folic acid and levothyroxine do not have a clinically significant drug-to-drug interaction.
Timing is crucial: You must separate the intake of levothyroxine and folic acid (especially if in a multivitamin with minerals like iron or calcium) by at least four hours to ensure proper absorption of the thyroid medication.
Levothyroxine is sensitive: Other substances, including certain foods, antacids, iron, and calcium, can interfere with levothyroxine absorption.
Benefits for cardiovascular health: Folic acid supplementation, when taken correctly with levothyroxine, can help lower elevated homocysteine levels, a cardiovascular risk factor common in hypothyroid patients.
Consider L-methylfolate: Hypothyroidism can impair the body's ability to convert folic acid to its active form, L-methylfolate. Some patients may benefit from taking the active form directly.
Always consult a doctor: Before adding any supplement, including folic acid, to your regimen, you should speak with your healthcare provider.

Is it Safe to Take Folic Acid and Levothyroxine?

It is generally safe to take folic acid with levothyroxine as there are no direct, clinically significant drug interactions. However, the timing of when you take them is crucial. Levothyroxine absorption can be affected by other substances, including certain foods and supplements.

The Importance of Separating Levothyroxine from Other Supplements

Levothyroxine is typically recommended to be taken on an empty stomach, 30 to 60 minutes before breakfast. Minerals found in some supplements, such as iron and calcium, can interfere with levothyroxine absorption by binding to it. To ensure proper absorption of levothyroxine, it's advised to take multivitamins or mineral supplements at least four hours after your levothyroxine dose. This also applies to folic acid if it's part of a multivitamin containing these minerals.

The Connection Between Hypothyroidism, Folate, and Cardiovascular Health

Patients with hypothyroidism often have lower folate levels and higher levels of homocysteine. Elevated homocysteine is a known risk factor for cardiovascular disease.

Here’s how they are linked:

Folate Metabolism: Thyroid hormone is needed to convert folic acid into its active form, L-methylfolate. Low thyroid function can impair this conversion process.
Homocysteine Regulation: Folic acid plays a vital role in breaking down homocysteine. Insufficient active folate can lead to a buildup of homocysteine.

Studies suggest that combining folic acid with levothyroxine can help reduce homocysteine levels more effectively in hypothyroid patients compared to taking levothyroxine alone. This indicates a potential cardiovascular benefit from folic acid supplementation in this population.

Beyond Standard Folic Acid: L-Methylfolate

Because hypothyroidism can affect the body's ability to convert standard folic acid, some individuals may benefit from taking L-methylfolate, the active form of folate. This can be particularly relevant for those with autoimmune thyroid conditions.

Best Practices for Taking Folic Acid and Levothyroxine

To ensure both medications are effective, consider these best practices:

Consistent Schedule: Take levothyroxine at the same time daily on an empty stomach.
Separate Dosing: Take folic acid or multivitamins at least four hours after your levothyroxine dose.
Active Folate Discussion: Talk to your healthcare provider about L-methylfolate if you have an autoimmune condition.
Regular Monitoring: Follow your doctor's guidance regarding levothyroxine dosage adjustments based on TSH levels.
Open Communication: Always inform your doctor and pharmacist about all medications and supplements you are taking.

Comparing Dosing Schedules


Feature	Separated Dosing (Best Practice)	Simultaneous Dosing (Poor Practice)
Levothyroxine Absorption	Maximized.	Reduced, especially with interfering minerals.
Effectiveness	Optimal for both medications.	Levothyroxine efficacy may be compromised.
Homocysteine Reduction	Optimal, supporting cardiovascular health.	Suboptimal due to compromised levothyroxine absorption.
Risk of Complications	Lower risk of complications associated with poorly controlled hypothyroidism.	Increased risk due to potential for ineffective treatment.
Expert Recommendation	Recommended.	Discouraged.

Conclusion

Taking folic acid with levothyroxine is safe in terms of direct drug interactions. However, proper timing is essential to prevent interference with levothyroxine absorption. Separating the doses by at least four hours helps ensure the effectiveness of your thyroid medication. Furthermore, for individuals with hypothyroidism, combining folic acid with levothyroxine may offer benefits in managing elevated homocysteine levels, a risk factor for cardiovascular disease. Always consult with a healthcare provider before adding new supplements to your routine.

To find more information on medication interactions, you can visit Drugs.com's interaction checker.

Frequently Asked Questions

Levothyroxine is best taken consistently at the same time each day, ideally on an empty stomach, 30 to 60 minutes before breakfast.

No, it is not recommended. You should separate your folic acid or multivitamin dose from your levothyroxine dose by at least four hours to prevent absorption interference.

Levothyroxine absorption can be inhibited by minerals like calcium and iron, which are often found in multivitamins. Separating the doses prevents these interactions, ensuring your body absorbs the full dose of thyroid hormone replacement.

Yes, some studies show a correlation between hypothyroidism and lower folate levels. Hypothyroidism can also impair the body's ability to metabolize folic acid into its active form.

Combining folic acid with levothyroxine therapy has been shown to reduce elevated homocysteine levels more effectively, which helps lower the risk of cardiovascular disease associated with hypothyroidism.

L-methylfolate is the active form of folate. Because some hypothyroid patients have trouble activating standard folic acid, L-methylfolate can be a more effective option. Discuss this with your doctor.

Taking them too close together can lead to reduced absorption of levothyroxine. If this happens occasionally, it may not cause issues, but doing so consistently could impact your thyroid hormone levels and medication effectiveness.

If you have hypothyroidism and your doctor suspects a deficiency or elevated risk, they may order tests for folate and homocysteine levels to determine if supplementation is needed.