Rifampin

What is this medication for?

• Combination therapy: atypical mycobacteria, resistant Staph (endocarditis, deep pyoderma with amoxi/clav or TMP/sulfa), actinomycosis, rhodococcosis
• Atypical mycobacterial infections (combination)

How is it given?

Give exactly as your veterinarian prescribed — never change the dose or stop on your own unless your veterinarian has told you to.

• Rule zero: rifampin is never given alone — resistance develops catastrophically fast; pair per susceptibility.
• The massive CYP induction makes it the classic "drug that makes other drugs disappear" — recheck doses of immunosuppressants, antifungals, and anticoagulants whenever rifampin starts or stops.

What if I miss a dose?

• Give it as soon as you remember — unless it is almost time for the next dose (then skip the missed one; never double up).
• Call your clinic if you miss more than one dose in a row.

Side effects — what should I watch for?

Effects listed as common in this handout

• Orange body fluids (Expected, harmless)

Worth a phone call to your veterinarian

• ↑ liver enzymes, stomach/intestinal distress, rashes (Uncommon but real)
• Hepatotoxicity (serious) (Preexisting liver disease risk)

⚠️ Contact your veterinarian or an emergency clinic IMMEDIATELY if you notice

• Trouble breathing, collapse, seizures, severe vomiting or diarrhea, facial swelling, or pale gums

Before starting (or refilling), tell your veterinarian if your pet:

• has or has had: Rifamycin hypersensitivity
• has or has had: Hepatic dysfunction (reduce dose); monotherapy forbidden — resistance emerges within days

• is pregnant, nursing, or used for breeding
• is taking any other medications, supplements, or flea/tick products, including:
  • ALL CYP450-metabolized drugs (cyclosporine, ketoconazole/itraconazole, corticosteroids, digitoxin, warfarin, theophylline, barbiturates, midazolam, propranolol, chloramphenicol, TMPS, doxycycline...)
  • Azole antifungals
  • Hepatotoxic drugs

Storage and handling

Room temperature, light-resistant. Orange-red discoloration of urine/tears/saliva expected — warn owners.

Good to know

• Rule zero: rifampin is never given alone — resistance develops catastrophically fast; pair per susceptibility.
• The massive CYP induction makes it the classic "drug that makes other drugs disappear" — recheck doses of immunosuppressants, antifungals, and anticoagulants whenever rifampin starts or stops.
• Body fluids turn orange — a harmless side effect that terrifies uninformed owners (stain warning for contact lenses/fabric).
• Intracellular niche (mycobacteria, Rhodococcus inside macrophages) is its clinical identity alongside the combination rule.