Chills after a flu shot

After vaccination, the immune system can become active and cause temporary tiredness, a mild fever, muscle aches, headache, or chills. These effects usually begin soon after the injection and settle as your body recovers. An inactivated vaccine cannot give you influenza, although you can catch influenza or another infection around the same time by coincidence.

Rest and drink fluids. Wear comfortable layers and check your temperature if you feel feverish. A cool cloth may help if you feel hot. Ask a pharmacist or clinician which pain or fever medicine is appropriate for you, particularly if you are pregnant, have liver or kidney disease, take blood thinners, or have allergies. Do not repeat a dose or stop regular treatment because of chills without advice.

Call emergency services for trouble breathing, swelling of the face or throat, widespread hives, fainting, severe dizziness, or sudden collapse. Contact a clinician if chills are intense, symptoms keep worsening, fever is high or persistent, or you develop a new concerning symptom. A sore arm and mild tiredness are common; symptoms that are severe or do not improve should be reviewed.

Ask whether your symptoms fit a vaccine reaction, how to monitor them, which medicines are safe with your conditions, and whether a future dose needs special planning. Tell the clinician when the chills began and whether you have had vaccine reactions before.