Reasoning GP · Algorithm · 1-page summary
Dry mouth (xerostomia) in adults
For: adults with dry mouth in primary care. Not for: children (a child with suspected type 1 diabetes → same-day paediatric diabetes team); dry eyes have their own dry eye protocol.
Core rule: most dry mouth is drug-induced, but dry mouth with dry eyes needs ANA + anti-Ro/La, and an unexplained persistent parotid or submandibular swelling needs urgent ENT. Never put it down to age, medicines or anxiety without checking.
0Stop — 999 or same day — thirst, polyuria and weight loss
- Dry mouth with thirst, passing a lot of urine and weight loss: capillary glucose today, with blood ketones if glucose is raised. Do not wait for HbA1c or a fasting glucose.
- Drowsy or breathing fast → 999 Raised ketones, vomiting or unwell → Same-day hospital
- Suspected type 1 diabetes → Same-day diabetes team; child or young person → same-day paediatric diabetes team (NICE NG18).
1Triage by pattern — first confirm true dryness, not thirst
| Pattern | Action |
|---|---|
| New or added drug | Medication review and ACB score; reduce or switch where feasible |
| Plus dry eyes | ± joint or systemic symptoms → ANA, anti-Ro/La, baseline bloods; rheumatology / oral medicine |
| Gland swelling | Unexplained and persistent → Urgent ENT (local suspected-cancer pathway) |
| Thirst, polyuria | Glucose today → block 0 |
| After radiotherapy | Saliva substitute, dental-led fluoride; oral medicine / hospital dentistry |
2Screen — one row is enough
- Unilateral firm painless parotid mass, facial weakness, fixation, rapid enlargement, skin involvement or neck nodes → Urgent ENT. No CT, MRI or biopsy first unless the local pathway says so.
- Known Sjögren with new or asymmetric gland swelling, lymphadenopathy, B symptoms, purpura, cytopenias, new neuropathy or renal disease (lymphoma) → Urgent rheumatology / haematology
- Bilateral parotid enlargement of unknown cause → Urgent rheumatology
- Mucositis, ulcers, dry eyes or rash after allogeneic stem cell transplant (chronic GVHD) → Urgent haematology / transplant team
3Assess
☐ Full medicines list incl. OTC, herbal, recreational; ACB score ☐ Dry eyes, joints, rash, Raynaud's, neuropathy ☐ Mouth: cervical caries, candida, angular cheilitis, dentures ☐ Parotid and submandibular glands, neck nodes
Bloods: glucose/HbA1c, TFTs if indicated. Sicca suspected: ANA, anti-Ro/La, ESR/CRP, immunoglobulins + electrophoresis, FBC, U&E, LFTs, urine ACR. HIV/HCV by risk.
Not in primary care: lip biopsy, Schirmer or salivary-flow tests.
4Classify — only if the screen is negative
- Drug-induced (commonest) — antimuscarinics, tricyclics, antipsychotics, sedating antihistamines, diuretics, opioids, paroxetine → reduce or switch (e.g. oxybutynin → mirabegron).
- Sjögren — dry mouth + dry eyes ± arthralgia, often a middle-aged woman. Anti-Ro supports, never confirms → rheumatology / oral medicine.
- Diabetes, dehydration, hypothyroidism, mouth breathing → treat the cause.
- Sarcoidosis, IgG4-related disease, HIV — bilateral gland enlargement → targeted tests and specialist; no steroids for a raised IgG4.
- Head and neck radiotherapy — often permanent → oral medicine / hospital dentistry.
- Uncertain — say so; review after any medicine change and re-examine the glands.
5Treat today — doses: NICE/SPC, BNF, local formulary
- Saliva substitute or stimulant by preference and formulary; neutral-pH (fluoride-containing where available) if natural teeth. Check ACBS criteria.
- Sips of water (unless fluid restricted); sugar-free gum or lozenges if gland tissue remains. No acidic sweets if dentate; alcohol-free mouthwash.
- Candida: confirm on examination; miconazole oral gel first line, nystatin if unsuitable or on warfarin; fluconazole if extensive (check interactions). Treat dentures too; out overnight.
- Pilocarpine: consider only after SPC check (airway disease, glaucoma/iritis, cardiac, peptic ulcer, renal/hepatic) and residual gland function; start low.
6Refer routinely
- Dental assessment for high caries risk; high-fluoride toothpaste and varnish are dental-led.
- Rampant caries, recurrent candida, denture problems, post-radiotherapy → specialist dental / oral medicine.
- Suspected Sjögren → rheumatology / oral medicine. HbA1c ≥48 mmol/mol → diabetes pathway. Low mood → NHS Talking Therapies.
7Never reassure by
- Blaming medicines, age or anxiety without asking about dry eyes.
- A parotid lump being painless.
- A single test: anti-Ro supports but does not confirm; a normal IgG4 excludes nothing.
- Long-standing Sjögren swelling that is now asymmetric or growing.
- A plan to "come back for fasting bloods" when thirst, polyuria and weight loss are present.
- Skipping dental review: caries progress rapidly in a dry mouth.
8Safety-net — say it, then document it
999 “Call 999 if you are vomiting and drowsy or breathing fast.” Same day “Contact us the same day for a gland swelling that grows quickly, becomes painful, hot or red, or comes with fever or weakness of one side of the face; or for great thirst, passing a lot of urine and weight loss.”
This week “Book an appointment if a lump in a gland or the neck does not go away, or for weight loss, night sweats, a rash of small purple spots or new numbness.”
✓Safe to leave primary care only if — all five, documented
No block 0–2 row applies; glucose checked if thirsty
Glands and neck nodes examined; dry eyes asked
Medicines and ACB score reviewed
Dental review and fluoride advice arranged
Safety-net given; review after any medicine change booked
Summary of the full Reasoning GP dry mouth algorithm, which holds the detail, causes, classification criteria and evidence. Sources: BSR Sjögren disease guideline 2024; ACR/EULAR 2016; NHS SPS artificial saliva and hydroxychloroquine monitoring; RCOphth 2020; NICE NG30, NG18. Clinical reference — follow local pathways and check doses: NICE/SPC, BNF.