MHRA Yellow Card scheme
The Yellow Card scheme is the MHRA's system for collecting reports of suspected side effects and other safety problems with medicines and healthcare products, and anyone in the UK can use it.
Full definition
The Yellow Card scheme is run by the Medicines and Healthcare products Regulatory Agency (MHRA). It collects reports of suspected side effects of medicines and vaccines, incidents involving medical devices, defective or fake medical products and safety concerns with e-cigarettes. The MHRA describes it as an early warning system. Anyone can report, whether you are a patient, a parent or carer, or a healthcare professional, and you do not need your doctor's permission. Reports can be made on the Yellow Card website or through the Yellow Card app. The MHRA asks reporters to include as much detail as possible, including other medicines, when symptoms started, treatment dates, and in particular whether a side effect continued or started after treatment was stopped. Individual reports matter because together they shape what regulators do. Finasteride is a clear example. By 5 April 2024 the MHRA had received 426 Yellow Card reports of sexual dysfunction with finasteride, and in almost half the outcome was recorded as "not recovered" or "not resolved". Those reports were part of the evidence behind the April 2024 Drug Safety Update, the patient alert card now in finasteride packs, and the further warnings issued in May 2026 for finasteride and dutasteride; see our MHRA safety updates and side effects pages. If you think a hair loss medicine has caused a side effect, including symptoms that have continued after stopping (see post-finasteride syndrome), you can report it yourself and should also tell your prescriber or GP.
What it does not mean
A Yellow Card report is a suspicion, not proof. The MHRA states that suspected adverse reactions reported to it "do not necessarily mean that the medicine has caused the reaction". The number of reports is also not a measure of how common a side effect is: the Propecia SmPC notes that the frequency of side effects found through spontaneous reports cannot be determined. A low count does not mean a side effect is unimportant, and a high count does not prove a link.
UK regulatory source
MHRA, About the Yellow Card scheme; MHRA Drug Safety Updates, 29 April 2024 (finasteride) and 11 May 2026 (finasteride and dutasteride); GOV.UK, Every report counts: support the Yellow Card scheme; Propecia 1 mg SmPC section 4.8