Fainting on your period: what it may mean

Period pain can trigger a reflex that lowers blood pressure and heart rate. Blood loss may contribute to anaemia, while nausea, poor appetite, vomiting or diarrhoea can reduce fluid and food intake. These explanations are possible rather than a diagnosis. A heart-rhythm problem can also cause fainting and needs consideration when there is little warning.

At the first sign of faintness, lie down and raise your legs. Move away from heat, loosen restrictive clothing and ask someone to stay with you. After you are completely alert, sip fluids and eat a small snack if you can swallow safely. Track bleeding, pain, cycle timing and any medicine taken.

Seek urgent help for very heavy bleeding, severe or one-sided pelvic pain, possible pregnancy, chest pain, breathlessness, a severe headache, injury, confusion or repeated fainting. Book a medical review if episodes recur, periods are unusually heavy, or tiredness and breathlessness persist between periods.

Ask whether you need blood tests for anaemia or glucose, a heart check, or assessment of painful or heavy periods. Bring a record of pad or tampon changes, clots, pain severity, meals, fluids and the time you recovered.