Reasoning GP · Algorithm · 1-page summary
Taste disorders — loss of taste and distorted taste
For: adults with loss of taste (ageusia, hypogeusia), distorted (dysgeusia) or phantom taste. Not for: smell loss alone → loss of smell algorithm.
Core rule: most "loss of taste" is loss of smell, and the commonest fixable cause is a drug — but taste change with facial weakness, cranial-nerve signs or drug toxicity is never "just viral".
0Stop — call 999 now — stroke, seizure, sepsis on chemotherapy, toxicity
- Facial weakness with limb weakness, speech disturbance or forehead sparing (stroke); seizure, reduced consciousness or meningism; rapidly progressive bulbar or breathing symptoms → 999
- Fever or unwell on chemotherapy (neutropenic sepsis) → 999 / immediate acute oncology or ED; do not wait for an FBC. Unstable digoxin or lithium toxicity → 999. Suspected DKA → Same-day emergency
1Triage — loss or distortion? taste or smell?
| Pattern | Meaning → next step |
|---|---|
| "No flavour" but tastes sweet, salt | Smell loss → loss of smell + drug/oral review |
| No sweet/salt/sour/bitter, or one side | True loss — rarer, more often CN VII/IX or structural → block 2 |
| Metallic or bitter | Drug review; digoxin or lithium? → block 2 |
| Recurrent tastes, no stimulus | ?Focal seizure aura → neurology |
2Screen — one row is enough
- Facial palsy: Bell's within 72 h → oral corticosteroid + eye care. Ear pain, vesicles, hearing loss or vertigo (Ramsay Hunt) → Same-day specialist; antiviral ideally ≤72 h.
- Dysphagia, dysarthria, palatal weakness, tongue deviation/wasting or several cranial nerves → Urgent neurology / ENT + imaging
- Hoarseness ≥45, unexplained neck lump, persistent oral ulcer, lump or red/white patch → Suspected cancer pathway; dysphagia → urgent upper-GI.
- One-sided nasal blockage, bleeding, facial pain, orbital symptoms, mass → Urgent ENT
- Metallic taste + vomiting, visual change, confusion, bradycardia (digoxin) or tremor, ataxia (lithium) → Same day ECG, level, U&E; withhold.
- Mouth ulcers or sore throat on methotrexate → withhold, Same-day FBC.
3Assess
☐ Taste vs smell; onset; viral/COVID; head injury ☐ All medicines incl. OTC, supplements, terbinafine in past 12 months ☐ Mouth: dryness, candida, glossitis, dentures ☐ CN VII, IX/X, XII; ear, nose, neck
Bloods by risk only: HbA1c, TFTs, B12/folate, FBC/ferritin, U&E/LFTs; zinc if deficiency risk; HIV by risk. Not routinely: zinc, ESR/CRP, taste-solution or smell tests, COVID serology, CD4.
4Classify — only if the screen is negative
- Post-viral / COVID (commonest) — often with smell loss; recovery variable over months → olfactory training ≥12 weeks.
- Drug-induced — metronidazole, metformin, ACE inhibitors, clarithromycin, terbinafine, lithium → review with the prescriber.
- Oral and dry mouth — candida, periodontal disease, anticholinergic burden → treat the cause, dental review.
- Nutritional or systemic — zinc, B12, folate, iron; diabetes, hypothyroidism, CKD, liver disease, Sjögren's → targeted tests, treat the cause.
- Neurological — Bell's, ear/parotid surgery, dental anaesthesia, head injury, MS → blocks 0–2.
- Uncertain — say so; unexplained beyond 3 months → consider MRI brain (NICE NG127) ± ENT.
5Treat today — doses: NICE/SPC, BNF, local formulary
- Culprit drug: stop, reduce or switch if safe, with the prescriber; never stop important treatment automatically.
- Confirmed candida: miconazole oral gel (check warfarin, statins) or nystatin; fluconazole 50 mg daily for 7 days if extensive or severe.
- Zinc, B12, folate, iron: confirmed deficiency only. No empirical high-dose zinc, omega-3 or steroids for post-viral dysgeusia.
- Flavour: umami, herbs, spices, texture; plastic cutlery, bicarbonate rinse if metallic; oral hygiene; stop smoking.
6Refer routinely
- Unexplained loss beyond 3 months → consider MRI brain (NICE NG127) and ENT; do not routinely refer if imaging is normal or loss began straight after a head injury.
- Persistent post-viral loss despite olfactory training → consider ENT. Burning mouth, chronic candida → oral medicine; Sjögren's → rheumatology.
- Weight loss or malnutrition risk → dietitian. Low mood → NHS Talking Therapies.
7Never reassure by
- "It's only taste" without asking about face weakness, ear pain, swallowing and speech.
- No ear vesicles — Ramsay Hunt can occur without them.
- A digoxin level in range: toxicity occurs within range.
- A planned FBC in a patient on chemotherapy with fever.
- Taste or smell loss alone as a sign of Parkinson's — refer only with motor features.
8Safety-net — say it, then document it
999 “Call 999 if your face droops with arm or leg weakness or slurred speech, or you have a fit. If you have a fever or feel unwell during chemotherapy, call your oncology helpline or 999 now.”
Same day “Contact us today for new face weakness, ear pain or a rash in or around the ear, trouble swallowing or speaking, eye pain or an eye you cannot close; or, on digoxin or lithium, sickness, confusion, blurred vision or shakiness.”
Within a week “Book an appointment if your taste gets worse, or you get a hoarse voice, a neck lump, a mouth ulcer or patch lasting over 3 weeks, one-sided nose blockage or bleeding, or weight loss.”
✓Safe to leave primary care only if — all five, documented
No block 0–2 row applies
Taste vs smell established
Full medicines review done
Mouth, cranial nerves, ear, nose and neck examined
Safety-net given; review booked (3 months post-viral; 4–8 weeks after a drug change)
Summary of the full Reasoning GP taste disorders algorithm (loss of taste and distorted taste), which holds the detail, causes, treatment by cause and evidence. Sources: NICE NG127, NG12, NG188, NG71, CG151, NG239; NICE CKS. Clinical reference — follow local pathways and check doses: NICE/SPC, BNF.