Drugs that harm the mouth
- Drugs
Many common medicines dry the mouth, swell the gums, stain teeth, cause ulcers or thrush, or alter taste. A drug history explains many oral problems.
What it is
Oral adverse effects of drugs are frequent and often missed. Dry mouth is the most common, from anticholinergic and many other drugs, and leads to caries. Gingival overgrowth follows phenytoin, ciclosporin and calcium channel blockers. Tetracyclines stain developing teeth; chlorhexidine and iron liquids stain the surface. Candidiasis follows antibiotics and inhaled or systemic corticosteroids. Oral ulcers can be caused by methotrexate, NSAIDs, nicorandil and some targeted cancer drugs. Lichenoid reactions follow antihypertensives, antimalarials and others. ACE inhibitors cause angioedema of the lips and tongue and altered taste. Sugar-containing liquid medicines cause caries in children. Antiresorptives can cause osteonecrosis of the jaw.
What to know
- Dry mouth: anticholinergics, antidepressants, antipsychotics, antihistamines, diuretics, opioids.
- Gingival overgrowth: phenytoin, ciclosporin, calcium channel blockers.
- Tooth staining: tetracyclines (intrinsic, during development); chlorhexidine, iron (extrinsic).
- Ulcers: methotrexate, NSAIDs, nicorandil; aspirin held on the gum burns it.
- Angioedema: ACE inhibitors, even after years of use.
Risks and precautions
- ACE inhibitor angioedema does not respond well to antihistamines and can obstruct the airway.
- Methotrexate mouth ulcers may be the first sign of toxicity, especially with dosing errors or kidney impairment.
- Long-term sugar-containing syrups in children with chronic conditions need sugar-free alternatives.
Next step / Initial management
- Take a full drug history for every oral complaint, including over-the-counter and herbal products.
- Discuss alternatives with the prescriber when a drug causes significant oral harm; do not stop essential drugs without them.
- Lip or tongue swelling on an ACE inhibitor: treat as angioedema, stop the drug and refer urgently if the airway is involved.
- Mouth ulcers on methotrexate: check blood count and renal function and refer urgently to the prescriber.
Test yourself
Think of the answer, then tap the question to see it.
Which drug class causes angioedema of the lips and tongue even after years of use?
ACE inhibitors.
What can new mouth ulcers in a patient on methotrexate indicate?
Methotrexate toxicity, which needs blood count and renal function checks.
Which antiseptic mouthwash stains the teeth with long-term use?
Chlorhexidine.
Connections
Educational content; it does not replace assessment by a dentist or doctor and is not a clinical instruction. For facial or neck swelling with difficulty swallowing or breathing, a knocked-out tooth or bleeding that will not stop, go to an emergency department at once.
Sources: Xerostomia (StatPearls Publishing (NCBI Bookshelf), 2023); Drug-Induced Gingival Overgrowth (StatPearls Publishing (NCBI Bookshelf), 2022); Tetracycline (MedlinePlus, US National Library of Medicine, 2026); Chlorhexidine Topical (MedlinePlus, US National Library of Medicine, 2026); Physical and Chemical Lesions of the Oral Mucosa (StatPearls Publishing (NCBI Bookshelf), 2025).
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Representative model, for educational purposes only.