For most people there is no known cause of ITP, but for others, particularly children it can follow a simple viral infection such as a cold or sore throat. It has a slightly higher incidence in pregnancy and can also arise whilst taking some medications or following vaccinations. ITP can also occur as a secondary condition to certain other illnesses.

All patients with ITP should be advised to seek medical attention if they have a prolonged (over 30 minutes) nosebleed which will not stop despite pinching the nose; prolonged gum bleeding; blood in the faeces or urine; a heavy blow to the head; persistent or severe headache with loss of vision, vomiting or drowsiness; and with women, very heavy periods (e.g. lasting 8–10 days, changing more than 9 tampons/pads per day, changing protection during the night, passing clots on 2 consecutive days)

Signs of a decreased platelet count include the following: pin prick rash of blood spots (petechiae), bruising, nosebleeds, gum bleeds, black mouth blisters, fatigue, heavy periods.

Patients with ITP should avoid certain over-the-counter drugs that can affect platelet function, including aspirin, ibuprofen and the blood-thinning medication warfarin. They should also be advised to limit their intake of alcohol because consuming too much alcohol can adversely affect blood clotting.

Further investigations or referrals include checking patients for the presence of Helicobacter pylori, a Gram-negative spiral bacterium that is present in nearly half the world’s population and associated to immune thrombocytopenic purpura. Eradication of Helicobacter pylori infection has been variably associated with a platelet response in patients with immune thrombocytopenic purpura (ITP). Responses occur in approximately half of ITP patients infected with this bacterium.