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uk Health & medical scares shaking chills • rigors • severe shivering episode • fever with shaking • sudden severe illness • suddenly much sicker • feels seriously wrong • rapid worsening illness • not like a normal cold • not like a typical flu • very unwell very fast • confusion with fever • breathless with chills • shivering and low temperature • high temperature chills adult • severe weakness with fever • reduced urination when ill • chills with chest symptoms • chills with urinary symptoms • worsening after seeming better

What to do if…
you develop shaking chills and feel suddenly much sicker than a typical viral illness

Short answer

Treat this as urgent: get same-day medical assessment now. If you have any emergency “red flag” symptoms (below), call 999 or go to A&E immediately.

Do not do these things

  • Do not “sleep it off” if you feel rapidly worse, unusually weak, confused, or can’t stay awake.
  • Do not delay care by repeatedly re-checking your temperature or waiting for medicine to “kick in”.
  • Do not drive yourself if you feel faint, confused, very weak, or are shivering hard—get help with transport.
  • Do not take leftover antibiotics or someone else’s prescription (it can delay correct treatment and tests).
  • Do not take more than the recommended dose of paracetamol/ibuprofen, or mix medicines without checking labels.
  • Do not drink alcohol or take sedating drugs to “knock yourself out”.

What to do now

  1. Check for emergency “red flags” right now. Call 999 / go to A&E if any apply:
    • Acting confused, slurred speech, not making sense, or difficult to wake
    • Blue, grey, pale or blotchy skin, lips, or tongue
    • Difficulty breathing, breathlessness, or breathing very fast
    • A rash that does not fade when you roll a glass over it
    • You collapse, can’t stay upright safely, or you feel you are rapidly deteriorating
  2. If you do not have the red flags above, still treat this as urgent. Call NHS 111 now if any apply:
    • You feel very unwell or like there’s something seriously wrong
    • You have not had a pee all day (adult/older child)
    • You keep vomiting and cannot keep fluids down
    • There is swelling or pain around a cut/wound, or a new rapidly worsening area of redness
    • You have a very high or low temperature, feel hot or cold to the touch, or are shivering
  3. Contact NHS 111 now (online or by phone) and say:
    “I have shaking chills/rigors and I feel suddenly much sicker than a typical viral illness.”
    If you cannot get through and you’re worsening, escalate to A&E / 999.
  4. While you’re waiting for advice/transport, do a 60-second “status check” and write it down:
    • When symptoms started and how fast you worsened
    • Temperature (if you can), and whether you feel very hot or very cold
    • Breathing: breathless at rest? breathing much faster than normal?
    • Thinking: can you answer simple questions clearly (name/date/place)?
    • Urine today: normal vs much less/dark
    • New severe pain (chest, abdomen, back/flank), stiff neck, or relentless vomiting/diarrhoea
  5. Make it easier for clinicians to act quickly (pack and prepare):
    • Photo of your medication list (including OTC meds), allergies, major conditions, pregnancy status
    • Recent events: infection symptoms, wounds, dental problems, recent surgery, new meds, recent travel, sick contacts
    • If you’re immunocompromised (chemo, steroids, transplant, asplenia, sickle cell, advanced kidney disease, etc.), say so early—this can change urgency.
  6. Get support and reduce risk while you wait:
    • Ask someone to stay with you (or stay on the phone) until you’re assessed.
    • Sip fluids if you can keep them down; don’t force large volumes if nauseated.
    • If you can take them safely, you may take paracetamol for fever/aches (follow the label), but don’t let symptom relief delay getting assessed.
  7. If symptoms escalate, switch to emergency care.
    If you become confused, very breathless, develop a non-fading rash, collapse, or you’re rapidly deteriorating: call 999.

What can wait

  • You do not need to figure out the exact cause (flu vs. kidney infection vs. pneumonia vs. something else) right now.
  • You do not need to decide about tests or treatments—your job is to get assessed urgently.
  • You can sort work, childcare logistics, and messages to others after you’ve secured medical evaluation.

Important reassurance

Shaking chills and a sudden step-change in how ill you feel can happen with infections that need prompt treatment. Getting checked quickly is a sensible, protective move—not an overreaction.

Scope note

These are first steps to get you safely assessed and to avoid dangerous delays. Further decisions depend on examination and tests.

Important note

This is general information, not a diagnosis. If you are worried you may be seriously unwell, worsening quickly, or showing red-flag symptoms, seek urgent emergency care.

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