Reporting supplement side effects: how the MHRA Yellow Card scheme works

The Medicines and Healthcare products Regulatory Agency (MHRA) runs the UK's pharmacovigilance system. Its core public-facing tool is the Yellow Card scheme at yellowcard.mhra.gov.uk, where anyone (patient, carer, or healthcare professional) can report a suspected side effect.

What the scheme covers#

Yellow Card accepts reports for:

• Prescription medicines
• Over-the-counter medicines
• Herbal and homeopathic products
• Vaccines
• E-cigarettes
• Medical devices
• Food supplements suspected of causing harm

That last category matters here. Most "biohacking" supplements are sold as food supplements, regulated by the Food Standards Agency, not as medicines regulated by the MHRA. But suspected adverse reactions to them can still be reported, and those reports help the MHRA identify safety signals.

What gets reported#

The scheme accepts reports of anything you suspect was caused by a product, even if you're not certain. You don't need a clinician to confirm. Useful information to include:

• The product name and brand
• Dose and how long you'd been taking it
• The reaction (symptoms, severity, timeline)
• Other medications or supplements you were taking
• Whether the reaction stopped when you stopped the product

Reports go into a national database. Patterns across multiple reports help the MHRA identify problematic products.

What the data is used for#

Examples of Yellow Card-driven action:

• Detection of safety signals in newly licensed medicines.
• Identification of contaminated or mislabelled supplements (especially weight-loss and "natural" sexual-performance products that have been found to contain undeclared prescription drugs).
• Tracking of vaccine safety post-rollout.
• Identification of clusters of harm from particular supplement categories.

Why it matters in the supplement market#

Food supplements in the UK are not regulated to medicine standards. Quality varies widely. Independent testing of online supplements has repeatedly found undeclared active ingredients, wrong doses, and contamination. The Yellow Card system is one of the few national mechanisms that catches harm patterns from this market. But it relies on people actually reporting.

If you've experienced an adverse reaction to a supplement and don't report it, the regulator can't see the pattern.

How to file a report#

• Web: yellowcard.mhra.gov.uk
• App: Yellow Card (free, iOS and Android)
• Paper forms: available from GPs and pharmacies

The process takes 5–10 minutes for a clear report. You can submit anonymously or with your details for follow-up.

What the scheme isn't#

• It's not a complaints procedure for unsatisfying products (no effect, bad taste, expensive). Use Trading Standards or consumer review channels.
• It's not a way to get medical care. If you're unwell, contact NHS 111 (or 999 in an emergency).
• It's not a refund mechanism. The MHRA doesn't deal with consumer disputes.

Why we link it on supplement pages#

The Biohacking Bible auto-renders a Yellow Card callout on every supplements section page. The reason is straightforward: we cover supplements that are legally available, but the regulatory bar for "available" is much lower than the bar for "tested safe at population scale". The MHRA scheme is one mechanism by which the market self-corrects when products turn out to cause harm. Pointing readers at it is part of our duty of care as an educational publisher in this space.

If you take supplements and experience anything unexpected (palpitations, mood changes, GI symptoms, skin reactions) and you can't account for them otherwise, a Yellow Card report is the right step.