VetSheet

L-Lysine

(S)-2,6-Diaminohexanoic acid

Nutritional Supplement

Reviewed by the VetSheet Veterinary TeamUpdated May 15, 2026Evidence-based veterinary reference

Dosing by species

Dosing data for this drug is not yet available in the VetSheet formulary. Every other section below is complete. Consult the current product label before prescribing.

Overview

L-Lysine is an essential amino acid commonly used in veterinary medicine, particularly for cats, to help suppress the replication of feline herpesvirus-1 (FHV-1) and alleviate associated respiratory and ocular symptoms.

Safety & warnings

Adverse effects

  • Gastrointestinal upset
  • Diarrhea

VetSheet drug reference is intended for licensed veterinary professionals as a clinical decision-support aid, not a substitute for professional judgement or the manufacturer’s current label.