How can folate supplementation cause a rash?

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Last updated: April 4, 2025 • View editorial policy

From the Research

Folate supplements can cause a rash in some individuals due to an allergic reaction to the supplement itself, and if you develop a rash after taking folate supplements, you should discontinue use and consult your healthcare provider. This hypersensitivity reaction occurs when the immune system overreacts to the folate or to inactive ingredients in the supplement formulation. Symptoms typically appear as red, itchy skin eruptions that may be localized or spread across the body. The reaction is more common in those with previous allergic tendencies or sensitivities to medications, as discussed in the context of adverse drug reactions 1. In rare cases, folate can cause more severe allergic reactions including hives, facial swelling, or difficulty breathing, which require immediate medical attention, similar to anaphylaxis reactions described in 2 and managed with epinephrine, antihistamines, and corticosteroids, as studied in 3. For those who need folate supplementation but experience skin reactions, alternative forms of folate (such as methylfolate) or food sources rich in natural folate might be better tolerated. Some key points to consider include:

  • The typical recommended dose of folic acid is 400-800 mcg daily for most adults, but higher doses may increase the risk of reactions in sensitive individuals.
  • Diagnostic tools for assessing allergic rashes are evolving, with research into hyperspectral imaging and in vitro tests for drug allergies, as mentioned in 4.
  • It's crucial to approach each case with careful consideration of the patient's history and potential for severe reactions, as certain populations like those with atopic dermatitis may have different endotypes and responses to treatments, as noted in 4. Given the potential for severe reactions, it's essential to prioritize caution and consult healthcare providers when managing folate supplementation and allergic reactions, considering the latest guidance on anaphylaxis management 3.

References

Research

Adverse drug reactions - allergy? side-effect? intolerance?

Australian family physician, 2013

Research

Anaphylaxis: Recognition and Management.

American family physician, 2020

Research

Managing anaphylaxis: Epinephrine, antihistamines, and corticosteroids: More than 10 years of Cross-Canada Anaphylaxis REgistry data.

Annals of allergy, asthma & immunology : official publication of the American College of Allergy, Asthma, & Immunology, 2023

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