PanicStation.org
UK USA
uk Health & medical scares

What to do if…
you have a fever and your heart rate feels unusually fast at rest

Produced and maintained by PanicStation.org Published: Last reviewed: Editorial policy UK guide

Short answer

If you have a fever and your heart rate feels unusually fast while resting, get urgent medical triage now. Call 999 or go to A&E for severe symptoms; otherwise call 111 where available, use NHS 111 online in England, or contact your local urgent care service today.

Do not do these things

  • Don’t exercise, take a hot bath, use a sauna, or drink alcohol to “sweat it out”; these can raise your heart rate and worsen dehydration.
  • Don’t take extra doses of paracetamol or ibuprofen. Use only the packet directions, or follow advice already given to you by a clinician.
  • Don’t accidentally double-dose by taking cold or flu remedies that already contain paracetamol or ibuprofen.
  • Don’t ignore worsening symptoms because the fever is not very high. Feeling seriously unwell with a fast pulse still matters.
  • Don’t drive yourself to A&E if you feel faint, confused, very weak, breathless, or have chest pain. Call 999 or ask someone else to take you.

What to do now

  1. Do one calm 60-second check and write it down.

    • Measure your temperature if you can.
    • Count your pulse for a full 60 seconds while seated and resting.
    • Note whether you have chest pain or pressure, severe breathlessness, fainting or near-fainting, new confusion, extreme shivering, a rash that does not fade when pressed, skin that looks mottled, very pale, blue, or grey, or not peeing normally. On brown or black skin, colour changes may be easier to see on the palms of the hands or soles of the feet.

  2. Choose the urgent route.

    • Call 999 or go to A&E now if you have chest pain, severe breathlessness, fainting, new confusion, blue, grey, pale, or blotchy skin, a non-fading rash, you feel you might collapse, or you think you might have sepsis.
    • Call 111 where available, use NHS 111 online in England, or contact your local urgent care service now if you are stable but worried, your pulse feels unusually fast at rest with fever, you are getting worse, you cannot keep fluids down, or the infection feels unlike a usual illness for you.

  3. While arranging help, reduce strain on your body.

    • Sit upright, or lie down if you feel dizzy.
    • Keep the room comfortably cool, not cold.
    • Sip water or another suitable fluid steadily. If you are vomiting, take tiny sips often.
    • If safe for you, take paracetamol or ibuprofen exactly as directed on the packet.

  4. Treat higher-risk situations as needing urgent assessment.

    • Seek urgent triage sooner if you are pregnant or recently had a baby, miscarriage, termination, or pregnancy loss.
    • Seek urgent triage sooner if you are having chemotherapy, take medicines that lower your immune system, take long-term steroids, have significant heart, lung, kidney, liver, blood, or immune disease, have diabetes with concerning symptoms, or recently had surgery, an invasive procedure, a wound, or a medical line or catheter.

  5. Use one clear sentence when you speak to triage.

    • Say: “I have a fever and my heart rate feels unusually fast at rest. My temperature is __ and my pulse is __. I also have __.”

What can wait

  • You do not need to work out the exact cause right now.
  • You do not need to decide whether this is viral, dehydration, anxiety, flu, COVID, or sepsis before asking for help.
  • You do not need to keep rechecking your pulse every few minutes once you have written it down.
  • Decisions about work, school, travel, or routine appointments can wait until you have been triaged and are stable.

Important reassurance

A faster heart rate can happen with fever, pain, dehydration, stress, and common infections. It is still sensible to act when it feels unusually fast for the temperature, especially if you feel seriously unwell or are getting worse.

Scope note

This is first-steps-only guidance to help you stabilise the moment and reach the right level of care. Later decisions, tests, and treatment depend on clinical assessment.

Important note

This is general information, not a diagnosis, and not medical or other professional advice. If you think you are deteriorating, trust that instinct and seek urgent help.

Additional Resources

Closely connected guides that may be useful during the same situation or its immediate aftermath.

About this guide

This guide was produced and is maintained by PanicStation.org using its published editorial process. Official and specialist sources are checked where relevant, and AI-assisted tools may be used for drafting, organisation, and consistency checks. The site operator remains responsible for publication, revision, and removal decisions.

Support us