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What to do if…
you are on blood thinners and develop a new headache or unexplained bruising

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

Short answer

Contact a clinician promptly today if you are taking a blood thinner and develop a new headache or unexplained bruising. Call 911 now for stroke signs, fainting, a seizure, unusual difficulty staying awake, bleeding that will not stop, or severe or worsening symptoms after a head injury. Go to an emergency department now after a fall or head bump, even if symptoms seem mild or there is no visible bleeding.

Do not do these things

  • Do not wait for emergency symptoms to pass on their own.
  • Do not stop, skip, double, or change your blood thinner dose unless a clinician gives you instructions.
  • Do not start or add aspirin, ibuprofen, naproxen, or other NSAIDs unless a clinician or pharmacist says they are safe for you.
  • Do not add new over-the-counter medicines or supplements before checking with a clinician or pharmacist.
  • Do not drive yourself if you feel faint, confused, unusually sleepy, unsteady, or unable to see or speak normally.

What to do now

  1. Call 911 now if you have emergency signs. These include:

    • a sudden severe headache
    • new weakness or numbness on one side, facial droop, trouble speaking, confusion, vision trouble, or new loss of balance
    • fainting, a seizure, or unusual difficulty staying awake
    • bleeding that will not stop
    • severe weakness, dizziness, or lightheadedness
    • severe or worsening symptoms after a fall, car crash, sports impact, or head bump

  2. Go to an emergency department now after a fall or head bump.

    • Do this even if the injury seemed minor, symptoms seem mild, or you cannot see any bleeding.
    • Call 911 rather than driving if symptoms are severe, you feel faint or confused, or you cannot travel safely.

  3. Get immediate medical advice for other serious bleeding signs.

    • Contact a clinician immediately if you vomit blood or material that looks like coffee grounds, have red or black tarry stools, have red or brown urine, or have a bruise that is rapidly spreading or becoming large.
    • Go to an emergency department if you cannot get immediate advice.
    • Call 911 rather than driving if symptoms are severe or you feel faint, weak, confused, or unsafe to travel.

  4. Contact a clinician promptly today for a new headache or unexplained bruising without the signs above.

    • Call the clinician who prescribes your blood thinner, your anticoagulation clinic, or your primary care office.
    • Say: “I take a blood thinner and I have a new headache or unexplained bruising.”

  5. Gather your medication details.

    • Find the exact name and dose of every prescribed blood thinner, including anticoagulant or antiplatelet medicines.
    • Note when you took your last dose.
    • Gather your medication bottles and a list of prescription medicines, over-the-counter medicines, vitamins, and supplements.

  6. If you take warfarin, ask whether you need a prompt PT/INR check.

    • Bring your INR log or anticoagulation-clinic details if you have them.

  7. Note other bleeding signs to report.

    • Look for bruises that are spreading or getting bigger, gum bleeding, frequent nosebleeds, unusually heavy menstrual bleeding, red or brown urine, red or black stools, vomiting blood, dizziness, or weakness.
    • Note when the symptoms started and where the bruises are.

  8. Reduce the chance of another injury while you arrange care.

    • Avoid activities where you could fall or hit your head.
    • Ask someone to stay with you or check on you while you wait for medical help, especially after an injury or if symptoms worsen.

What can wait

  • You do not need to decide whether to stop blood thinners long-term.
  • You do not need to identify the cause of the headache or bruising before seeking help.
  • You do not need to try new pain medicines before contacting a clinician.
  • You do not need to contact several services at once. Start with 911 for emergency signs, an emergency department after a fall or head bump, or one prompt clinical contact for other symptoms.

Important reassurance

Bruising can happen more easily while taking blood thinners, but a new headache or unexplained bruising deserves prompt attention. Seeking advice does not mean you have to make a long-term medication decision now. It gives a clinician the information needed to decide what care is appropriate.

Scope note

These are first steps only. Testing, medication changes, and later decisions may need help from your clinician or another specialist.

Important note

This is general information, not a diagnosis or legal, medical, financial, therapeutic, or other professional advice. Call 911 for emergency signs or seek prompt clinical care if symptoms are new, worsening, or concerning.

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.

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