Carbamazepine
Severe
Textbook-cited
Reduced chloramphenicol efficacy
Avoid concurrent use or increase dose with monitoring
Source: KDT 7e · p949
Drug reference
Chloramphenicol
Amphenicol antibiotic / bacteriostatic (bactericidal at high concentrations) · Antibiotic
Also known as Chloromycetin, Chloroptic, Phenicol
START
IV 50-100 mg/kg/day in 4 divided doses; reserve for situations where safer antibiotics are contraindicated or ineffective; check baseline CBC and LFTs
TYPICAL MAX
4 g/day; 100 mg/kg/day for meningitis
STOP IF
CBC abnormalities (reticulocytopenia, leukopenia, thrombocytopenia), signs of aplastic anemia, optic symptoms, 14 days maximum unless exceptional circumstances
WATCH
CBC every 2-3 days (reticulocyte count, WBC, platelets), LFTs, drug levels if available (target 10-20 mcg/mL peak), vision symptoms
CDSCO approvedSchedule HATC J01BA01
KDIGO 2024 + manufacturer label
- ONSET
- 1h · Rapid distribution and onset
- PEAK
- 1h · Peak after oral dose
- t½
- 4h · 4 hours (adults)
- DURATION
- 6h · 6-8 hour dosing interval
EXCRETION
Renal (5-10%, unchanged)
route + CYP
INTERACTIONS
12 major
SEVERE in our sources
PREGNANCY
Avoid in pregnancy especially third trimester; risk of gray baby syndrome; only if no safer alternative
FDA category + note
Top interactionssee all 12 →
- CarbamazepineSevereTextbook-citedKDT 7e · p949
- GlibenclamideSevereTextbook-citedKDT 7e · p949
- GliclazideSevereTextbook-citedKDT 7e · p949
- GlimepirideSevereTextbook-citedKDT 7e · p949
Available in India
198 branded formulations and 66 fixed-dose combinations. Look up specific brands in the Drugs workspace.
Mechanism
Reversibly binds to 50S ribosomal subunit, inhibiting bacterial peptidyl transferase and blocking peptide bond formation and protein synthesis. Broad spectrum of activity including Gram-positive, Gram-negative, anaerobes, and atypicals (Rickettsia, Mycoplasma, Chlamydia).
Indications
Meningitis (when penicillin-allergic or H. influenzae resistant)Rickettsial diseases (typhus, Rocky Mountain spotted fever)Bacterial meningitis (H. influenzae, N. meningitidis, S. pneumoniae)Brain abscessAnaerobic infections (Bacteroides fragilis)PlagueBartonelosisTopical: bacterial conjunctivitis, external ear infections
Dosing
- Adult
- IV: 50-100 mg/kg/day in 4 divided doses (max 4 g/day). Meningitis/brain abscess: 100 mg/kg/day. PO: 250-500 mg QDS
- Pediatric
- >2 weeks: 25-50 mg/kg/day IV in 4 divided doses. Avoid in neonates <2 weeks (gray baby syndrome)
- Renal adjustment
- No adjustment needed; hepatically metabolized
- Hepatic adjustment
- Reduce dose; avoid or use extreme caution in hepatic impairment
- Geriatric
- Standard dosing; monitor CBC and LFTs closely
- Max dose
- 4 g/day (adults); 100 mg/kg/day (meningitis)
Pharmacokinetics
Onset
Rapid bacteriostatic effect
Peak effect
IV: immediate distribution; Oral: 0.5-2 hours (Tmax)
Duration
6-8 hours
Half-life
Adults: 4 hours; Neonates: 24 hours (immature glucuronidation)
Bioavailability
Oral: 75-90%; excellent tissue penetration including CSF and CNS
Protein binding
50-60%
Metabolism
Hepatic glucuronidation (90%) to inactive metabolites
Excretion
Renal (5-10% unchanged); fecal (majority as metabolites)
Contraindications
- Hypersensitivity to chloramphenicol
- Pregnancy (especially third trimester)
- Breastfeeding (avoid if possible)
- Pre-existing bone marrow depression
- G6PD deficiency (may cause hemolysis)
- Optic nerve disease
- Infants under 2 weeks (gray baby syndrome risk)
Side effects
Common
NauseaVomitingDiarrheaBitter tasteOral candidiasisTopical: burning, stinging
Serious
- Bone marrow suppression (dose-related, reversible)
- Aplastic anemia (idiosyncratic, rare but fatal - 1:25,000 to 1:40,000)
- Gray baby syndrome (neonates - cardiovascular collapse)
- Optic neuritis
- Peripheral neuritis
- Hypersensitivity reactions
- Superinfection
Pregnancy & lactation
Pregnancy
Avoid in pregnancy especially third trimester; risk of gray baby syndrome; only if no safer alternative
Lactation
Excreted in breast milk; avoid if possible; may cause bone marrow suppression in infant
Drug interactions
Glibenclamide
Severe
Textbook-cited
Hypoglycemia
Monitor blood glucose; reduce sulfonylurea dose
Source: KDT 7e · p949
Gliclazide
Severe
Textbook-cited
Hypoglycemia
Monitor blood glucose; reduce sulfonylurea dose
Source: KDT 7e · p949
Glimepiride
Severe
Textbook-cited
Hypoglycemia
Monitor blood glucose; reduce sulfonylurea dose
Source: KDT 7e · p949
Glipizide
Severe
Textbook-cited
Hypoglycemia
Monitor blood glucose; reduce sulfonylurea dose
Source: KDT 7e · p949
Phenobarbital
Severe
Textbook-cited
Reduced chloramphenicol efficacy
Avoid concurrent use or increase dose with monitoring
Source: KDT 7e · p949
Rifampicin
Severe
Textbook-cited
Reduced chloramphenicol efficacy
Avoid concurrent use or increase dose with monitoring
Source: KDT 7e · p949
Cyp Substrates
Severe
Textbook
Prolonged half-lives of drugs metabolized by CYPs.
Recognize this effect to avoid severe toxicity and potentially fatal outcomes.
Source: G&G 14e · p1189
Penicillin
Severe
Textbook
Apparent antagonism on pneumococci; higher mortality in pneumococcal meningitis compared to penicillin alone.
Avoid combination for highly sensitive organisms where cidal drug alone is sufficient.
Source: KDT 7e · p699
Avapritinib
Severe
Database
Drug interaction classified as: metabolism
Source: DDInter
Benzhydrocodone
Severe
Database
Drug interaction classified as: metabolism
Source: DDInter
Brigatinib
Severe
Database
Drug interaction classified as: metabolism
Source: DDInter
Related guidelines
Skin and soft tissue infections
IDSA · Infectious Diseases · 2010
Extrapulmonary tuberculosis
ICMR · Infectious Diseases · 2022
Dengue fever
ICMR · Infectious Disease · 2022
Empirical antimicrobial use in common syndromes
ICMR · Infectious Diseases · 2019
Antimicrobial resistance — clinical roadmap
MOHFW · Infectious Diseases · 2012
Ask House about Chloramphenicol
Continue into a citation-backed clinical answer with the drug context already attached.
Sources: KD Tripathi 7e, Goodman & Gilman 14e, Harrison 22e, Katzung·Verified: 2026-05-19 · House clinical team·Cockpit curated: 2026-05-19