Sick-day rules — what to increase, pause, never stop & monitor
Acute intercurrent illness — fever, vomiting, diarrhoea, dehydration, infection — destabilises many long-term conditions. Some drugs must be increased (steroids), some paused to protect the kidneys (SAD MANS), some are time-critical and must never be stopped (insulin, levodopa, anti-epileptics), and several need extra monitoring or dose review (lithium, digoxin, DOACs, warfarin). This is the one place to check the rule, counsel the patient, and copy the advice into the record.
Adrenal crisis is a medical emergency
Vomiting, severe illness, drowsiness or collapse in a steroid-dependent patient → 100 mg IM hydrocortisone immediately and call 999. Never withhold steroid in a sick adrenal-insufficient patient because of a missing diagnosis. When in doubt, give hydrocortisone.
👥 Who needs steroid sick-day rules
- Primary adrenal insufficiency — Addison's disease.
- Secondary adrenal insufficiency — pituitary disease, or long-term exogenous steroids suppressing the axis.
- Anyone on oral prednisolone ≥5 mg/day (or equivalent) for ≥4 weeks, recently stopped long-term steroids, or on regular high-dose inhaled/topical/intra-articular steroids.
- Congenital adrenal hyperplasia; post-bilateral adrenalectomy.
Every such patient should hold a NHS Steroid Emergency Card and ideally a hydrocortisone injection kit with training.
🤒 Moderate illness (oral rules)
- Fever/infection needing antibiotics, or feeling significantly unwell.
- Double the usual oral glucocorticoid dose until recovered (usually 24–72 h after the fever settles), then return to normal.
- Minor illness without fever (e.g. common cold): usually no change needed.
🤮 Can't keep tablets down → inject
- Vomiting or diarrhoea = oral steroid not absorbed. Don't wait.
- Give 100 mg hydrocortisone IM (adult) and seek urgent medical help / call 999.
- Patient/carer should be trained to self-administer the emergency injection.
📋 Patient advice — copy into the record / message
"You have a condition where your body can't make extra steroid when you're ill, so you must do it yourself. If you have a fever or infection, double your steroid dose until you're better. If you are vomiting or have diarrhoea, or feel very unwell, use your emergency hydrocortisone injection and call 999 — don't wait. Always carry your Steroid Emergency Card and tell any healthcare professional you are steroid-dependent."
The golden rule: never stop insulin
In type 1 diabetes, insulin must never be stopped during illness — even if not eating. Stress hormones push glucose and ketones up, and stopping insulin precipitates diabetic ketoacidosis. Illness usually means the patient needs the same or more insulin, not less.
🩸 Core diabetes sick-day rules (insulin or hypo-causing drugs)
- Keep taking insulin — never omit basal insulin; correction doses are often needed.
- Test glucose more often — at least every 2–4 hours, including overnight if unwell.
- Check ketones (blood ketone meter preferred) if type 1, or if glucose is persistently >15 mmol/L / the patient is unwell.
- Maintain hydration & carbohydrate — aim ~3 L of sugar-free fluid; if not eating, replace meals with carb-containing drinks (milk, fruit juice, sugary drinks).
- Treat the underlying illness and rest.
⏸️ Drugs to hold in diabetes during dehydrating illness
- SGLT2 inhibitors ("-flozin") — stop; risk of euglycaemic DKA.
- Metformin — stop if dehydrated (lactic-acidosis / AKI risk).
- Sulfonylureas (gliclazide) & GLP-1 agonists — review/reduce if not eating (hypo / nausea).
📞 When to escalate
- Persistent vomiting — can't keep fluids/carbs down.
- Ketones rising or >3.0, or glucose uncontrolled despite correction.
- Drowsy, abdominal pain, deep/laboured breathing, fruity breath → ?DKA, 999.
- Unable to follow the plan / lives alone and deteriorating.
📋 Patient advice — copy into the record / message
"When you're ill, keep taking your insulin — never stop it, even if you're not eating. Test your blood sugar every 2–4 hours and check ketones if you have a meter. Drink plenty of sugar-free fluids; if you can't eat, take sugary drinks instead of meals. Stop your '-flozin' (e.g. dapagliflozin) and metformin while you're dehydrated. Get urgent help if you keep vomiting, your ketones are high, you feel drowsy, or you have tummy pain or fast breathing — this can be a diabetic emergency."
Pause during acute dehydrating illness
During vomiting, diarrhoea, or fevers/sweats/shaking severe enough to cause dehydration, temporarily stop the drugs below to reduce the risk of acute kidney injury, DKA (SGLT2 inhibitors) and metformin-associated lactic acidosis. Restart when eating and drinking normally for 24–48 h. This is for short-term illness — not a reason to stop chronic therapy.
🔤 The "SAD MANS" drugs to hold
Sulfonylureas
gliclazide, glimepiride — hypo risk if not eating
ACE inhibitors
ramipril, lisinopril, perindopril
Diuretics
furosemide, bendroflumethiazide, spironolactone
Metformin
lactic acidosis risk if dehydrated/AKI
ARBs
losartan, candesartan, irbesartan
NSAIDs
ibuprofen, naproxen, diclofenac
SGLT2 inhibitors
dapagliflozin, empagliflozin — DKA risk
⚠ Special caution — SGLT2 inhibitors
- Stop the "-flozin" during any acute illness, dehydration, or before surgery.
- Risk of euglycaemic DKA — ketones can be high with near-normal glucose.
- Advise: check ketones if able, seek help if unwell, vomiting, abdominal pain or breathless.
🩸 Don't stop these
- Insulin — never stop in type 1 diabetes; follow diabetes sick-day rules (more frequent monitoring, correction doses, ketone testing).
- Most other regular medicines continue unless advised otherwise.
📋 Patient advice — copy into the record / message
"While you are unwell with vomiting, diarrhoea or a high fever, stop these tablets until you are eating and drinking normally again for a couple of days: [list the patient's relevant SAD MANS drugs]. This protects your kidneys. Keep taking your insulin if you use it. Restart your usual tablets once you've recovered. If you can't keep fluids down, are getting more unwell, passing little urine, or feel drowsy, contact us or call 111/999."
Time-critical medicines — do not stop or delay
Some drugs cause serious harm if missed, delayed or abruptly stopped during illness. If the patient can't swallow or is vomiting, find an alternative route — don't just omit them. These are the medicines hospitals flag as "critical" / "must be given on time".
🧠 Parkinson's — levodopa & PD drugs
- Must be given on time (NICE NG71, Parkinson's UK "Get It On Time"). Late/missed doses cause severe immobility, swallowing/breathing problems.
- Never stop abruptly — risk of an akinetic crisis / neuroleptic-malignant-like syndrome.
- If nil-by-mouth or vomiting: use dispersible levodopa, a rotigotine patch, or an NG tube — get specialist/Parkinson's nurse advice for dose conversion.
- For nausea use domperidone / ondansetron — avoid metoclopramide & prochlorperazine (worsen Parkinson's).
⚡ Epilepsy — anti-epileptic drugs
- Don't miss doses — abrupt withdrawal risks breakthrough seizures / status epilepticus.
- If vomiting: re-dose if vomited within ~1 hour; consider buccal/rectal or alternative route; seek advice for IV equivalents.
- Fever/illness lowers the seizure threshold — counsel on rescue medication (e.g. buccal midazolam) and the patient's seizure plan.
💉 Insulin & steroids
- Insulin — never stop in type 1 (see Diabetes tab); illness needs the same or more.
- Glucocorticoids / adrenal replacement — never stop; increase in illness (see Steroids tab).
🩸 Anticoagulants & others
- Anticoagulants (DOAC / warfarin) — don't simply stop; balance clot vs bleed and review renal function/INR (see Monitor tab).
- Immunosuppression / biologics, antiretrovirals (HIV), anti-rejection (tacrolimus, ciclosporin) — continue unless a specialist advises otherwise; seek advice early.
- Long-term opioids, baclofen, clonidine, beta-blockers — abrupt withdrawal causes harm; don't stop suddenly.
Narrow-therapeutic-index drugs — review dose & monitor
These drugs aren't simply held or doubled — dehydration, AKI, fever and interacting antibiotics shift their levels, so they need extra monitoring or a dose review during illness.
🧂 Lithium
- Dehydration (D&V, fever, sweats) and reduced intake raise lithium levels → toxicity.
- Maintain salt & fluid intake; check a lithium level if significantly unwell; consider holding during marked dehydration on specialist advice.
- Watch the SAD MANS interactions — NSAIDs, ACEi/ARBs, thiazides all raise levels.
- Toxicity: coarse tremor, ataxia, slurred speech, vomiting, confusion → check level urgently.
❤️ Digoxin
- AKI and dehydration reduce clearance; hypokalaemia (D&V or diuretics) potentiates toxicity.
- Check U&E and consider a digoxin level if unwell; watch nausea, visual changes, arrhythmia.
🩸 DOACs & warfarin
- DOACs are renally cleared (especially dabigatran) — AKI causes accumulation and bleeding risk; reassess renal function and dose.
- Warfarin — acute illness, reduced intake, liver involvement and many antibiotics raise the INR; check INR during significant illness or new antibiotics.
💊 Other level-sensitive drugs
- Methotrexate — hold during serious infection/sepsis; avoid trimethoprim/co-trimoxazole (folate antagonism → marrow toxicity).
- Theophylline/aminophylline — fever and macrolides/ciprofloxacin reduce clearance → toxicity.
- Phenytoin, ciclosporin, tacrolimus, aminoglycosides — monitor levels/renal function in significant illness.
Sore throat, mouth ulcers, fever or flu-like illness on these drugs = possible agranulocytosis
Several drugs can cause sudden neutropenia / agranulocytosis. In a patient on one of them, a sore throat, mouth ulcers, fever, chills or other infection is an emergency until excluded: stop the drug and arrange an urgent (same-day) FBC. Counsel every patient to recognise these symptoms when you start the drug.
🦋 Antithyroid drugs — carbimazole / propylthiouracil
- Sore throat, mouth ulcers, fever, flu-like illness → stop immediately and get an urgent FBC the same day (MHRA warning).
- Do not restart until agranulocytosis is excluded; if confirmed, the drug is permanently contraindicated.
- Carbimazole also carries acute pancreatitis risk — stop if severe upper abdominal pain.
🧠 Clozapine
- Mandatory FBC monitoring scheme; any fever/infection → check FBC and consider sepsis.
- Infection & reduced intake can also raise clozapine levels (toxicity) — review dose; smoking cessation during illness raises levels too.
- Fever in the first weeks may be benign clozapine-induced, but always exclude neutropenia, myocarditis and sepsis.
💊 Immunosuppressants & DMARDs — hold during significant infection, seek advice
- Methotrexate, azathioprine, leflunomide, mycophenolate, sulfasalazine, ciclosporin, tacrolimus — usually pause during a serious/febrile infection; check FBC (neutropenia/marrow suppression); restart on specialist advice once recovered.
- Biologics (anti-TNF — adalimumab, etanercept, infliximab; rituximab, tocilizumab, ustekinumab) and JAK inhibitors (tofacitinib, baricitinib) — withhold during active infection; infection signs may be blunted, threshold for investigation/treatment is lower.
- Avoid trimethoprim/co-trimoxazole with methotrexate (folate antagonism → marrow toxicity).
- High-dose / long-term corticosteroids are immunosuppressive — fever may be masked; also remember steroid sick-day rules (Steroids tab).
- Live vaccines are contraindicated; consider PJP/atypical infection in the unwell immunosuppressed patient.
⚠ Other drugs that can cause agranulocytosis
- Carbamazepine, mirtazapine, sulfasalazine, sulfonamides/co-trimoxazole, deferiprone, dapsone, penicillamine, ganciclovir.
- Same rule: fever / sore throat / mouth ulcers → consider an urgent FBC and stop pending results.
🩸 Don't forget
- Neutropenic sepsis in a patient on chemotherapy or recent immunosuppression is a medical emergency → 999 / acute oncology, do not wait for tests.
- Fever also affects level-sensitive drugs (theophylline, phenytoin) — see Monitor tab.
📋 Patient advice — copy into the record / message
"While you take this medicine, a sore throat, mouth ulcers, high temperature, chills or feeling flu-like could be a sign your white blood cells have dropped. If that happens, stop the medicine and contact us urgently (the same day) for a blood test — don't wait. If you feel very unwell, shivery or can't get hold of us, call 111 or 999. Always tell any healthcare professional which medicine you're on."
Condition flare / self-management plans
Beyond individual drugs, several long-term conditions have NICE-backed self-management actions for when the patient is unwell. Make sure each has a written personalised plan and (where relevant) a rescue pack.
🌬️ Asthma
- Follow the personalised asthma action plan; step up reliever / preventer per the plan.
- Oral prednisolone rescue (e.g. 40 mg OD) for an acute attack as planned; seek help if reliever lasts <4 h or no better.
- Red flags: too breathless to talk, blue lips, exhausted → 999.
🫁 COPD
- Rescue pack: prednisolone for increased breathlessness; antibiotics if sputum is more purulent (Anthonisen criteria).
- Increase short-acting bronchodilator; use the written self-management plan; seek help if not improving in 48 h.
❤️ Heart failure
- Pause diuretics & ACEi/ARB during D&V/dehydration (SAD MANS) — but watch for fluid overload on recovery.
- Daily weights; restart and review when eating/drinking normally; recheck U&E.
🩹 Other plans
- Addison's / adrenal — steroid sick-day rules + emergency injection (see Steroids tab).
- IBD — flare plans; don't stop maintenance; steroid rescue per gastro plan.
- Epilepsy — rescue medication & seizure plan (see Never-stop tab).