What vitamins should not be taken with hydroxychloroquine?

October 7, 2025 •

3 min read

While hydroxychloroquine is a cornerstone medication for autoimmune conditions like lupus and rheumatoid arthritis, studies show it can affect nutrient levels in the body, primarily impacting vitamin D, B12, and calcium. It is crucial to understand what vitamins should not be taken with hydroxychloroquine or how to time them to prevent reduced medication effectiveness and other complications.

Quick Summary

Taking hydroxychloroquine requires careful timing of mineral supplements, particularly antacids containing calcium or magnesium, to avoid reduced effectiveness. It can also deplete vitamin D, B12, and folate over time, requiring monitoring and potential dietary adjustments. Grapefruit should be avoided completely.

Key Points

Timing of Mineral Supplements: Mineral-containing antacids and supplements (calcium, magnesium) should be taken at least 4 hours apart from hydroxychloroquine to prevent absorption interference.
Grapefruit is a Contraindication: Avoid grapefruit and grapefruit juice entirely, as they can significantly increase hydroxychloroquine levels and the risk of serious side effects like heart rhythm issues.
Monitor Vitamin D Levels: Long-term hydroxychloroquine use can interfere with the conversion of vitamin D to its active form, making regular monitoring and potential supplementation necessary.
Watch for B-Vitamin Depletion: The medication can also impact the absorption of vitamin B12 and folate, which may require monitoring, especially for those on long-term therapy.
Always Consult a Healthcare Provider: Never adjust your medication or supplement schedule without consulting a doctor or pharmacist to avoid harmful interactions and ensure treatment effectiveness.
Take HCQ with Food: To minimize stomach upset, it is recommended to take hydroxychloroquine with food or milk.

Understanding the Complexities of Hydroxychloroquine and Nutrients

Hydroxychloroquine, often sold under the brand name Plaquenil, is a disease-modifying antirheumatic drug (DMARD) used to manage autoimmune diseases such as rheumatoid arthritis, lupus, and Sjögren's syndrome. Its long-term use can, however, alter the body's handling of certain vitamins and minerals, necessitating a careful approach to supplementation. While there are no hard 'never take' vitamins for hydroxychloroquine, some supplements and minerals require specific timing, and certain foods or vitamins need to be avoided or monitored closely.

Critical Timing for Mineral Supplements

The most significant and well-documented interaction concerns minerals found in antacids and certain supplements. Products containing calcium, magnesium, or aluminum can interfere with the absorption of hydroxychloroquine, rendering the medication less effective. This is not a matter of avoiding these minerals entirely, but rather ensuring a sufficient time gap between taking them and your hydroxychloroquine dose.

The Grapefruit Warning

Beyond vitamins and minerals, a key food interaction to be aware of is grapefruit. Grapefruit juice can significantly increase the blood levels of hydroxychloroquine by inhibiting certain enzymes, which can heighten the risk of side effects, including cardiac arrhythmias. For this reason, consuming grapefruit or grapefruit juice should be strictly avoided during hydroxychloroquine therapy.

Potential Nutrient Depletions

Long-term use of hydroxychloroquine can affect the body's natural balance of several key nutrients. This is due to interference with absorption or metabolism mechanisms. The most commonly cited examples include:

Vitamin D: Hydroxychloroquine may inhibit the conversion of vitamin D to its active form. This can lead to a deficiency over time and reduced calcium absorption.
Vitamin B12: The medication may interfere with the intestinal absorption of vitamin B12. Patients on long-term therapy, especially those with pre-existing risk factors for B12 deficiency, should be monitored.
Folate: Similar to vitamin B12, there is evidence that hydroxychloroquine can reduce folate absorption.
Calcium and Magnesium: Beyond the timing issues with supplements, HCQ can decrease overall calcium absorption and alter magnesium metabolism.

These potential depletions underscore the need for regular monitoring through blood tests, especially for patients on long-term treatment. A healthcare provider can then recommend appropriate supplementation or dietary adjustments if needed.

A Guide to Common Vitamin and Supplement Interactions with Hydroxychloroquine


Nutrient/Substance	Interaction Type	Recommendation/Notes	Potential Outcome
Calcium Supplements/Antacids	Absorption Interference	Separate doses by at least 4 hours. Take HCQ first, then the supplement/antacid.	Reduced HCQ effectiveness if taken together.
Magnesium Supplements/Antacids	Absorption Interference	Separate doses by at least 4 hours. Preliminary evidence suggests caution with supplements.	Reduced HCQ effectiveness.
Grapefruit/Grapefruit Juice	Metabolism Inhibition	Avoid completely. Do not consume during HCQ therapy.	Dangerously increased HCQ levels, higher risk of irregular heartbeat.
Vitamin D	Metabolism Impact	HCQ can hinder activation. Regular monitoring of vitamin D levels is advisable, especially for those with low sun exposure.	Potential for vitamin D deficiency over time.
Vitamin B12	Absorption Interference	Monitor for deficiency symptoms (e.g., fatigue, weakness). Discuss supplementation with a doctor if concerns arise.	Potential for B12 deficiency.
Folate	Absorption Interference	Long-term users should monitor folate levels and discuss supplementation with their healthcare provider.	Potential for folate deficiency.

Conclusion: Safe Supplementation and Vitamin Management

Managing a vitamin and supplement routine while on hydroxychloroquine is less about absolute avoidance and more about strategic timing and diligent communication with your doctor. The most critical takeaway is to meticulously time any mineral-based supplements or antacids, allowing at least four hours between doses. The risks associated with grapefruit are significant and warrant complete avoidance. For vitamins like D, B12, and folate, the concern is long-term depletion, making regular monitoring of your levels a sensible precaution. Never start, stop, or significantly alter your supplement regimen without first consulting your healthcare provider, who can ensure your plan is both safe and effective for your specific health needs.

For more detailed information on drug interactions, always consult your physician or a reliable medical database like Drugs.com.

Frequently Asked Questions

Yes, but you should discuss the specific multivitamin with your doctor. The primary concern is not the vitamins themselves but the mineral content. High-dose calcium or magnesium in a multivitamin could interfere with absorption if taken too closely to your HCQ dose. Your doctor may advise spacing it out.

You should wait at least 4 hours between taking hydroxychloroquine and any antacids that contain calcium, magnesium, or aluminum. This time gap prevents the antacid from blocking the absorption of your medication.

Yes, hydroxychloroquine may reduce the conversion of vitamin D to its active form, which can lead to a deficiency over time. Patients on long-term therapy may benefit from having their vitamin D levels monitored by a healthcare professional.

Grapefruit and its juice can inhibit the enzymes that break down hydroxychloroquine, leading to higher concentrations of the drug in your bloodstream. This increases the risk of side effects, particularly dangerous heart rhythm issues.

While vitamin D may be beneficial if you have a deficiency, the timing of calcium is key. It's important to discuss the specific dosage and timing with your doctor to prevent the calcium from interfering with HCQ absorption. Your doctor can help you establish a safe schedule.

Some evidence for the related drug chloroquine suggests magnesium supplements might decrease drug effectiveness. While more research is needed for HCQ, it is wise to separate magnesium supplements and HCQ doses by several hours to be cautious.

No, hydroxychloroquine does not affect all vitamins equally. The main concerns are with minerals (like calcium and magnesium in antacids) and the potential long-term depletion of specific vitamins like D, B12, and folate, which requires careful monitoring, not immediate avoidance.