How often do liver enzymes abnormalize with tigecycline?

Short answer:
In the largest pooled analyses of tigecycline, mild elevations of liver enzymes (AST/ALT > 2‑3 × upper limit of normal) occurred in roughly 5‑10 % of patients, while serious or grade 3‑4 elevations (often defined as > 5‑10 × ULN or accompanied by jaundice) were seen in < 1 % of patients.

Why the numbers matter

These figures come from the pivotal phase III trials (for complicated intra‑abdominal infection and skin/soft‑tissue infection) as well as the post‑marketing surveillance data that the FDA and EMA review.

Practical take‑away

1. Baseline testing – A standard liver panel (AST, ALT, ALP, bilirubin) is recommended before starting tigecycline, especially if the patient has pre‑existing liver disease or is taking other hepatotoxic drugs.
2. Monitoring – Repeat liver enzymes are advised after 3–5 days of therapy and again at the end of treatment if the course is ≥ 7 days.
3. Interpreting results –
   • Mild rises (≤ 2‑3 × ULN) usually do not require stopping the drug.
   • Severe rises (> 5 × ULN) or any signs of jaundice (yellowing of skin/eyes, dark urine, pruritus) should prompt immediate evaluation and possibly drug discontinuation.
4. Drug‑specific caution – Tigecycline is not contraindicated in hepatic impairment, and the dose is not adjusted for liver dysfunction. However, because the drug can cause hepatic enzyme elevations, close monitoring is prudent.

Bottom line

• Mild elevations are relatively common (about 5–10 %) but generally benign.
• Severe elevations are rare (< 1 %) and, when they occur, usually require stopping the drug.

So, while you should watch liver enzymes during therapy, the overall risk of significant hepatotoxicity with tigecycline is low.