Heat Flashes and Chills: What They Can Mean and What to Do

Heat flashes and chills can reflect fever, hormonal changes, medicine effects, or a changing body temperature; the right response depends on the pattern and other symptoms. A person may feel suddenly hot, sweat, and then shiver as the body adjusts its temperature. The sensation can be brief or return in episodes.

An infection can cause chills when the body is raising its internal temperature, followed by warmth or sweating as that temperature changes. Influenza, pneumonia, a urinary tract infection, kidney infection, dengue fever, and malaria can all present with fever or chills, usually alongside other clues. Symptoms such as cough, sore throat, burning urine, back or side pain, headache, rash, or recent travel help guide the assessment.

Hot flashes without a measured fever may be linked to hormonal changes, stress, alcohol, spicy food, a warm room, or a medicine. Low blood sugar, dehydration, and an overactive thyroid are other possibilities. The feeling of being hot does not by itself confirm an infection, and chills do not identify one specific cause.

Rest in a comfortable room, drink fluids if you can, and use light layers that can be removed easily. Check your temperature with a thermometer during an episode and record when the flushing, sweating, or shivering occurs. Note new medicines, missed meals, alcohol, recent heat exposure, menstrual or menopausal changes, travel, and accompanying symptoms.

Do not bundle up heavily during a fever, and do not use ice-cold water if it causes more shivering. Take medicines only as directed on the label or by a clinician; avoid starting antibiotics without an assessment. Arrange a medical review if episodes keep returning, disturb sleep, or occur with unexplained weight change, persistent cough, urinary symptoms, or ongoing fatigue.

Seek urgent medical help for trouble breathing, chest pain, confusion, fainting, a seizure, severe weakness, blue or grey lips, or skin that is unusually cold and clammy. Urgent assessment is also needed for a rapidly worsening illness, severe headache with a stiff neck, repeated vomiting, severe abdominal pain, or a widespread rash with fever. These features can occur with serious infection, including sepsis, and should not be managed by monitoring at home.

Contact a clinician promptly after travel to a malaria-risk area if chills or fever develop, even if the illness seems mild. A clinician may check your temperature, examine you, review medicines and exposures, and decide whether blood or urine tests are needed.

Ask what causes best fit the timing of your episodes and whether you should keep a temperature and symptom diary. You can also ask whether a medicine, hormonal change, blood sugar problem, thyroid condition, or infection needs checking, and which warning signs should prompt same-day care.