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Will the vaccine affect my menstrual cycle?

The Medicines and Healthcare products Regulatory Agency (MHRA) is closely monitoring reports of menstrual disorders (period problems) and unexpected vaginal bleeding following vaccination against COVID-19 in the UK. These reports have also been reviewed by the independent experts of the Commission on Human Medicines’, COVID-19 Vaccines Benefit Risk Expert Working Group and members of the Medicines for Women’s Health Expert Advisory Group.  

The current evidence does not suggest an increased risk of either menstrual disorders or unexpected vaginal bleeding following the vaccines. 

A range of menstrual disorders have been reported after all three of the COVID-19 vaccines including heavier than usual periods, delayed periods and unexpected vaginal bleeding. The number of reports of menstrual disorders and vaginal bleeding is low in relation to both the number of females who have received COVID-19 vaccines to date and how common menstrual disorders are generally. The MHRA will continue to closely monitor reports of menstrual disorders and vaginal bleeding with COVID-19 vaccines. 

Advice about period problems and/or unexpected vaginal bleeding, including when to seek medical attention, is available at the NHS website