When should an adult go to the hospital for a fever?
Last updated September 3, 2026.
Go to the ER if a fever reaches 103F (39.4C) or more and will not come down, or if any fever arrives with trouble breathing, chest pain, stiff neck, severe headache, confusion, fainting, seizure, or a rash that does not blanch under pressure. Those pairings can mean meningitis or sepsis, and minutes matter. Otherwise, most adult fevers - a high temperature is 38C (100.4F) or above - are the immune system working and respond to rest, fluids, and acetaminophen or ibuprofen. Urgent same-day care fits a fever that keeps worsening despite home treatment, lasts beyond three days, or follows foreign travel, surgery, or a new drug. Pregnancy, age over 65, chemo, or immune suppression all lower the bar for getting seen. Pymander is a free AI doctor, 24/7 by text, and can help you judge your specific fever right now.
What to do
- Check for the emergency pairing: fever plus breathing trouble, stiff neck, confusion, seizure, or non-blanching rash means ER now.
- Treat the fever properly first: fluids, rest, and acetaminophen or ibuprofen - then reassess in a few hours.
- Mark day three: a fever still going after three days of home care needs a clinician.
- Lower your threshold if high-risk: pregnancy, age over 65, or immune suppression means call sooner.
Related questions
- How do you bring down a fever in adults?
- When is a rash an emergency?
- Can allergies cause a fever?
- When is a cough serious?