Dapsone and Rifampin: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Rifampin
Dapsone
How we grade severity & evidence
Severity levels
- Contraindicated: These should generally not be used together.
- Major: Potentially serious — often needs a change or close monitoring.
- Moderate: Can be significant — usually manageable with monitoring.
- Minor: Usually limited clinical impact.
Evidence grades
- Established: Well documented — supported by controlled studies or strong clinical data.
- Probable: Good supporting evidence, though not definitively proven.
- Suspected: Some evidence suggests this interaction, but it is not well established.
- Possible: Limited or conflicting evidence; the interaction may occur.
- Theoretical: Predicted from the drugs' pharmacology; not yet confirmed in people.
Ratings come from the documented interaction literature and are reviewed by a pharmacist. They describe the documented risk of the combination, not what will necessarily happen to you — your dose, timing, and health picture all matter.
What happens
Reduced dapsone exposure, reduced efficacy of dapsone, an increased hydroxylamine metabolite of dapsone and an increased the risk of methemoglobinemia
Interaction Deep Dive
Coadministration of rifAMPin may reduce dapsone exposure, may increase the clearance of dapsone and may also increase the production of the hydroxylamine metabolite of dapsone which could increase the risk of methemoglobinemia123. Concomitant use resulting in a decrease of dapsone serum concentrations and half-life 567 was reported to have no affect on clinical effectiveness 6.
Why it happens (mechanism)
Increased hepatic metabolism
Literature reports
3 reports — tap to read
a) Concomitant dapsone and rifAMPin therapy has been reported to result in a decrease in dapsone plasma half-life. Following 2 weeks of rifAMPin therapy, dapsone plasma half-life was decreased from 24 to 11 hours. Increased plasma clearance rate was not due to a stimulated acetylation nor to displacement of dapsone from plasma protein binding sites. It was postulated that the observed interaction was due to microsomal enzyme induction caused by rifAMPin 4.
b) It was observed that neither dapsone acetylation nor plasma clearance rate predisposed patients to develop dapsone resistance 4.
c) Concomitant use resulting in a decrease of dapsone serum concentrations and half-life 567 was reported to have no affect on clinical effectiveness 6.
Common questions
Can I take Dapsone and Rifampin together?
Reduced dapsone exposure, reduced efficacy of dapsone, an increased hydroxylamine metabolite of dapsone and an increased the risk of methemoglobinemia Always confirm with your pharmacist or prescriber before making any change.
How serious is the Dapsone and Rifampin interaction?
It is rated major. Potentially serious — often needs a change or close monitoring.
How quickly could this interaction happen?
The documented onset is "delayed". Effects tend to build up gradually over days to weeks.
How strong is the evidence for this interaction?
The evidence is graded "theoretical". Predicted from the drugs' pharmacology; not yet confirmed in people.
Questions for your pharmacist
- Does my dose of Dapsone or Rifampin need adjusting while I take them together?
- What symptoms should prompt me to call you or my prescriber right away?
- Does the timing of my doses matter for this combination?
- Is there a safer alternative to one of these medications for me?
References (7)
- Product Information: RIFADIN(R) IV intravenous injection, rifampin intravenous injection. sanofi-aventis US LLC (per FDA), Bridgewater, NJ, 2023. DailyMed
- Product Information: RIFADIN(R) oral capsules, rifampin oral capsules. sanofi-aventis US LLC (per FDA), Bridgewater, NJ, 2023. DailyMed
- Product Information: RIFATER(R) oral tablets, rifampin, isoniazid, pyrazinamide oral tablets. sanofi-aventis US LLC (per FDA), Bridgewater, NJ, 2023. DailyMed
- Gelber RH & Rees RJ: Dapsone metabolism in patients with dapsone-resistant leprosy. Am J Trop Med 1975; 24:963-967. PubMed
- Pieters FA, Woonink F, & Zuidema J: Influence of once-monthly rifampicin and daily clofazimine on the pharmacokinetics of dapsone in leprosy patients in Nigeria. Eur J Clin Pharmacol 1988; 34:73-76. DOI
- George J, Balakrishnan S, & Bhatia VN: Drug interaction during multidrug regimens for treatment of leprosy. Indian J Med Res 1988; 87:151-156.
- Balakrishnan S: Drug interactions. The influence of rifampicin and clofazimine on the urinary excretion of DDS. Lepr India 1981; 53:17.
Keep reading about Rifampin
Keep reading about Dapsone
These medications also interact with supplements
Prescription drugs aren't the whole picture — herbal and dietary supplements can interact with them too. From the evidence-graded Natural Medicines database:
major · moderate · minor — check everything you take with our drug–supplement interaction checker.
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