Medications That Cause Toxic Hepatitis

Major Drug Categories and Specific Agents

Acetaminophen is the single most common cause of drug-induced liver failure, particularly at doses exceeding 4g per day, though hepatotoxicity can occur even at therapeutic doses in chronic alcohol users 1, 2
NSAIDs (including diclofenac, ibuprofen, naproxen, and indomethacin) account for approximately 10% of drug-induced hepatitis cases 1, 2
Isoniazid, rifampin, and pyrazinamide are first-line antituberculosis drugs that commonly cause drug-induced liver injury 3, 1, 2
Pyrazinamide is considered the most hepatotoxic among first-line tuberculosis agents 1, 2
Macrolide antibiotics including erythromycin, roxithromycin, and azithromycin cause cholestatic hepatitis 4
Methotrexate causes hepatotoxicity, particularly when combined with other hepatotoxic drugs including alcohol, azathioprine, and retinoids 5, 6, 2
Statins are hepatotoxic and increase methotrexate toxicity when used concomitantly 5, 6
Azathioprine causes hepatotoxicity and should be used cautiously with other hepatotoxic medications 5, 6
Retinoids are hepatotoxic and increase risk when combined with methotrexate 5, 6
Nevirapine causes severe hepatotoxicity, with grade 4 liver enzyme elevations occurring in up to 9.4% of patients, particularly in the first 12 weeks of therapy 7, 8
Protease inhibitors (ritonavir, ritonavir/saquinavir combinations) cause severe hepatotoxicity more frequently than indinavir, nelfinavir, or saquinavir alone 7, 8

Excessive alcohol consumption significantly increases risk, even if discontinued during treatment 1, 2
Underlying liver disease (including hepatitis B or C coinfection) predisposes patients to drug-induced hepatotoxicity 7, 8, 1, 2
Advanced age increases susceptibility, particularly with NSAIDs and methotrexate interactions 5, 6
Renal impairment increases risk, especially with renally eliminated drugs like methotrexate 5, 6
Obesity, diabetes, and hyperlipidemia increase risk, particularly with methotrexate 2
Female gender doubles the risk of nevirapine-associated hepatotoxicity 7, 8
Concomitant use of multiple hepatotoxic agents substantially increases risk 5, 7, 6, 8

Drug-induced hepatitis is suspected when ALT levels are ≥3 times the upper limit of normal with hepatitis symptoms, or ≥5 times the upper limit of normal without symptoms 3, 1, 2
For nevirapine, monitor liver enzymes every 2 weeks for the first month, then monthly for the first 12 weeks, and every 1-3 months thereafter 7
For methotrexate, perform regular laboratory monitoring (CBC and liver function tests) every 3-6 months 2

Immediately discontinue the suspected hepatotoxic medication when significant liver injury is detected (ALT ≥3× ULN with symptoms or ≥5× ULN without symptoms) 3, 1, 2
Stop all potentially hepatotoxic drugs including isoniazid, rifampin, and pyrazinamide if hepatitis occurs 3
Perform serologic testing for hepatitis viruses A, B, and C if not done at baseline 9
For acetaminophen overdose within 4 hours of presentation, administer activated charcoal prior to starting N-acetylcysteine 2
For mushroom poisoning (Amanita phalloides), consider penicillin G (300,000 to 1 million units/kg/day IV) and silymarin (30-40 mg/kg/day for 3-4 days) 9

In patients with liver cirrhosis, reduce acetaminophen dosage to 2-3g per day instead of the standard 4g maximum 1, 2
Avoid NSAIDs in patients with existing liver disease due to increased risk of hepatotoxicity and other adverse effects 1, 2
Use the lowest effective dose for the shortest duration possible for all potentially hepatotoxic medications
Avoid concomitant use of multiple hepatotoxic agents whenever possible, including alcohol 5, 6
For methotrexate patients, administer folic acid or folinic acid to reduce hepatic adverse effects 2

In patients requiring antituberculosis therapy, the hepatotoxic agents isoniazid, rifampin, and pyrazinamide should be administered when clinically indicated because of their proven efficacy, but they necessitate frequent clinical assessments and laboratory monitoring of liver enzymes to detect drug‑induced liver injury early. 10