Pharmacotherapy in Oral Medicine
On this page
Direct answer
A short list of drugs does most of oral medicine's work, and the examination tests the doses, the first-line choices and the interactions of exactly that list. Analgesia runs from paracetamol (500-1000 mg, up to 4 g daily) through ibuprofen (400 mg six to eight hourly); odontogenic infection begins with amoxicillin 500 mg three times daily, metronidazole 400 mg three times daily for anaerobes, and clindamycin or azithromycin for the penicillin-allergic; candidosis yields to topical nystatin or miconazole gel and systemic fluconazole 50-100 mg daily; herpes labialis responds to acyclovir 200 mg five times daily for five days if started early. Topical and systemic corticosteroids carry the immunological workload, and immunomodulators — dapsone, thalidomide, colchicine, tacrolimus — complete the ladder. The safe prescriber adds the interactions: miconazole and metronidazole with warfarin, metronidazole with alcohol, NSAIDs with peptic ulcer and anticoagulation.
What you must remember
- Analgesic doses: paracetamol 500-1000 mg every 6 hours, maximum 4 g daily (less with liver disease or alcohol use); ibuprofen 400 mg every 6-8 hours with food — avoided in peptic ulcer, renal impairment, aspirin-sensitive asthma and with anticoagulants.
- Antibiotic workhorses: amoxicillin 500 mg three times daily first-line for odontogenic infection; metronidazole 400 mg three times daily for anaerobic cover (no alcohol — disulfiram-like reaction); penicillin allergy — clindamycin 300 mg four times daily or azithromycin 500 mg once daily for three days; amoxicillin with clavulanate for spreading or refractory infection.
- Antifungal regimen: nystatin oral suspension 100,000 units four times daily, swished and swallowed; miconazole 2 per cent oral gel applied four times daily — it potentiates warfarin dangerously; fluconazole 50-100 mg daily for 7-14 days systemically; remove and disinfect dentures concurrently.
- Antiviral timing: acyclovir 200 mg five times daily for five days, effective only if started within about 72 hours of prodrome; valacyclovir 500 mg twice daily as the convenient alternative; higher prophylactic doses in immunocompromise.
- Corticosteroid ladder: topical triamcinolone 0.1 per cent, clobetasol 0.05 per cent and dexamethasone rinses for mucosal disease; systemic prednisolone about 40-60 mg daily, tapering, for severe erosive lichen planus and pemphigus.
- Immunomodulator markers: dapsone in mucous membrane pemphigoid (check G6PD and haemoglobin); thalidomide for severe HIV-associated aphthae (teratogenic, neuropathy — strict controls); colchicine and, in older Indian texts, levamisole for recurrent aphthous stomatitis; topical tacrolimus 0.1 per cent as steroid-sparing.
- Symptomatic staples: chlorhexidine 0.2 per cent rinse, benzydamine 0.15 per cent, viscous lidocaine 2 per cent, and compounded "magic mouthwashes" for mucositis — supportive, never curative.
One ulcer clinic, one safe prescribing session
A woman on warfarin presents with denture stomatitis and a traumatic ulcer. The tempting prescription — miconazole gel — is the classic error: miconazole inhibits warfarin metabolism and has produced fatal bleeds; the safe choice here is nystatin suspension (or fluconazole with INR monitoring agreed with the physician). Her ulcer pain: paracetamol rather than ibuprofen, since NSAIDs also perturb anticoagulation and risk gastric bleeding. A second patient, diabetic and allergic to penicillin, has a dentoalveolar abscess: drainage first — antibiotics never substitute for removing the source — then clindamycin in dental doses with a warning about diarrhoea. A third, immunocompetent with recurrent herpes labialis at day one of prodrome, gets acyclovir started now, because the same prescription on day four is placebo. The pattern across the three chairs: the right drug, the right dose, and the interaction checked before the pen moves.
Where students slip
The interaction pairings are where marks are lost and patients harmed: miconazole-warfarin and metronidazole-warfarin on one side, metronidazole-alcohol on the other, and NSAIDs atop anticoagulants for a third. The timing slip follows: antivirals for herpes labialis work within about 72 hours of onset, and "start at any stage" is the planted wrong option. The dose-recall slips cluster around paracetamol's 4 g ceiling (with the liver-disease caveat), acyclovir's five-times-daily regimen, and fluconazole's 50-100 mg span. Finally, the sequence question: an abscess is drained before it is prescribed for — candidates who answer antibiotics alone for a fluctuant swelling have inverted surgical principle, however correct the drug chosen.
Frequently asked questions
What is the first-line antibiotic for odontogenic infection, with dose?
Amoxicillin 500 mg orally three times daily; add metronidazole 400 mg three times daily for anaerobic spread, or use clindamycin in penicillin allergy.
Why is miconazole gel dangerous in a patient on warfarin?
Miconazole inhibits CYP2C9, potentiating warfarin and raising INR to bleeding levels — nystatin or a physician-agreed systemic alternative is safer.
What is the dose and timing of acyclovir for herpes labialis?
Acyclovir 200 mg five times daily for five days, started within 72 hours of the prodrome; later initiation has little effect on established lesions.
Which antifungal regimens treat oral candidosis?
Nystatin 100,000 units four times daily or miconazole 2 per cent gel topically; fluconazole 50-100 mg daily for 7-14 days when systemic therapy is needed.
Which immunomodulators treat severe recurrent aphthous stomatitis?
Colchicine, and in older Indian teaching levamisole; thalidomide for severe HIV-associated disease under strict teratogenicity controls; topical corticosteroids remain first-line.