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What to do if…
you develop new confusion or severe drowsiness after taking a new medicine

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

Short answer

If you are very hard to wake, have fainted or collapsed, are struggling to breathe, or have had a seizure, call 999 for an ambulance now. If it is not a 999 emergency, treat new confusion or severe drowsiness after a new medicine as urgent and use the urgent medical help route for where you are in the UK.

Do not do these things

  • Do not drive, cycle, cook, use tools, or operate machinery.
  • Do not drink alcohol, take recreational drugs, or take extra sedating medicines while you are trying to get advice.
  • Do not take another dose of the new medicine until you have urgent clinical advice, unless a clinician tells you to.
  • Do not make a long-term decision to stop a regular prescription abruptly if you are unsure; ask what to do about the next dose.
  • Do not give food or drink to someone who is very drowsy, confused, choking, vomiting, or hard to keep awake.
  • Do not stay alone if you might pass out, fall, or fall asleep uncontrollably.

What to do now

  1. Check for emergency signs and call 999 now if any of these apply:
    • the person cannot be kept awake or is hard to rouse
    • breathing is slow, noisy, gasping, or very difficult
    • lips, tongue, face, hands, or feet look blue, grey, or unusually pale
    • there has been a seizure, collapse, severe chest pain, or stroke-like symptoms such as face drooping, arm weakness, or speech problems
    • there is choking, repeated vomiting, or possible poisoning with severe symptoms
  2. If it is not a 999 emergency, get urgent same-day medical advice. In England, use 111 online if the person is aged 5 or over, or call 111; for a child under 5, call 111. Elsewhere in the UK, use the urgent health advice route for where you are.
  3. Say the key facts clearly: “new confusion or severe drowsiness after starting a new medicine,” the medicine name, the dose, and the time it was taken.
  4. Put the medicine information in one place:
    • the box, bottle, blister pack, label, and patient information leaflet
    • the exact name, strength, dose, and time taken
    • any recent dose change or first dose
    • all other medicines taken in the last 24 hours, including painkillers, antihistamines, cold and flu remedies, sleeping tablets, supplements, alcohol, and recreational drugs
  5. Make the next few minutes safer while you wait for advice:
    • sit or lie somewhere you cannot easily fall
    • ask someone to stay with you or keep you on the phone
    • keep your phone unlocked and within reach
    • if very drowsy but breathing normally, rest on your side rather than flat on your back
  6. If you may have taken the wrong dose, double-dosed, taken someone else’s medicine, or mixed medicines by mistake, tell 999, 111, or the urgent advice service immediately.
  7. If you can speak to a community pharmacist quickly, ask about side effects and interactions, but use 999 or urgent medical advice first if symptoms are severe, worsening, or frightening.

What can wait

  • You do not need to decide now whether to stop the medicine long-term, restart it later, or change treatment.
  • You do not need to search forums, compare side-effect stories, or work out the cause by yourself.
  • You do not need to report a suspected side effect today; reporting can wait until you are safe and more settled.
  • You do not need to solve the whole medicine plan now; the immediate job is staying safe and getting real-time clinical advice.

Important reassurance

New confusion or heavy drowsiness after a medicine can feel frightening, and it is reasonable to treat it seriously. Getting urgent advice is a safety step, not an overreaction.

Scope note

These are first steps only to help you stay safe and get rapid medical guidance. Later decisions about stopping, restarting, changing dose, or tapering a medicine may need help from a doctor, pharmacist, prescriber, or other appropriate clinician.

Important note

This is general information, not a diagnosis or personal medical advice. If you think you or someone with you is becoming unsafe, unresponsive, or rapidly worse, call 999.

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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