Measles rash after MMR: what should you know?

Some people develop a light, short-lived rash after MMR as the immune system responds to the vaccine. A low fever or swollen glands can occur with it. This vaccine-related rash is not the same as catching measles from the vaccine, because the vaccine does not cause ongoing measles infection.

Timing, appearance, fever, breathing symptoms and recent contact with someone unwell help a clinician distinguish a vaccine response from another infection. A rash after vaccination should not be diagnosed from a photograph alone.

Record when the rash began, where it started, whether it is spreading and whether fever or other symptoms are present. Encourage fluids and allow rest. Keep the skin cool, avoid scratching and use only products suitable for the person’s age. Contact a GP if the rash is worrying, persistent, worsening, or accompanied by significant illness.

Until advice is given, avoid close contact with people who are medically vulnerable if the rash is accompanied by fever or respiratory symptoms. Keep the vaccination record available.

Get emergency help for trouble breathing, swelling of the lips or face, collapse, a seizure, severe weakness or a rapidly worsening illness. These can indicate a serious reaction or another urgent problem. Seek prompt advice for a high or persistent fever, poor fluid intake, or a child who is unusually sleepy.

Ask whether the rash fits a vaccine response, whether school or nursery attendance should change, what symptom relief is suitable, and whether any household contact needs advice. Tell the clinician about allergies, medicines, previous vaccine reactions and possible measles exposure.