Isotretinoin
13-cis-retinoic acid
Also known as: Claravis · Amnesteem · Accure · Accutin · Curatane · Isoacne · Isohexal · Isotrex · Liderma · Nimegen · Oratane · Procuta · Roaccutane · Roacutan · Stiefotrex · isotretinoinum · 13-cis-retinoic acid · Ro4-3780
Reviewed by the VetSheet Veterinary TeamUpdated Apr 5, 2026Evidence-based veterinary reference
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Dosing by species
🌎 NA — North America🌍 EU — Europe
Dogs
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| Sebaceous adenitis when more conservative treatments have failed | 1 mg/kg PO q12h for one month; if improvement is noted reduce dose to 1 mg/kg PO once daily; long-term goal is to treat with either 1 mg/kg PO every other day or 0.5 mg/kg once daily | PO | q12h initially, then q24h or q48h | Long-term | 🌎 NA |
| Sebaceous adenitis | 1-3 mg/kg PO once a day to twice daily | PO | q12-24h | — | 🌎 NA |
| Schnauzer comedo syndrome | 1 mg/kg once daily or divided q12h PO | PO | q12-24h | — | 🌎 NA |
| Sebaceous adenitis in poodles; granulomatous sebaceous adenitis in viszlas | 1-2 mg/kg once daily or divided q12h PO | PO | q12-24h | — | 🌎 NA |
| Epitheliotrophic lymphoma, cutaneus lymphoma | 2 mg/kg once daily or divided q12h PO | PO | q12-24h | — | 🌎 NA |
| Schnauzer comedo syndrome, sebaceous adenitis in poodles, ichthyosis, keratocanthoma, epitheliotropic lymphoma, and sebaceous gland hyperplasia and adenoma | 1-3 mg/kg q12-24h PO | PO | q12-24h | — | 🌎 NA |
| Cutaneous lymphosarcoma | Isotretinoin at 3-4 mg/kg PO daily. Prednisone (1 mg/kg/day) may be useful to alleviate pruritus. Lomustine at 50 mg/m2 q21-30 days may be effective | PO | q24h | — | 🌎 NA |
- Cutaneous lymphosarcoma: See lomustine monograph for more information
Cats
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| Feline acne | 5 mg/kg PO once daily | PO | q24h | — | 🌎 NA |
| Feline acne | 10 mg per cat once daily PO | PO | q24h | — | 🌎 NA |
| Feline acne | 1-3 mg/kg q12-24h PO | PO | q12-24h | — | 🌎 NA |
| Epitheliotrophic lymphoma, cutaneus lymphoma | 10 mg/cat once daily PO | PO | q24h | — | 🌎 NA |
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Overview
Isotretinoin is a first-generation synthetic retinoid primarily utilized in veterinary dermatology for the management of severe disorders of keratinization and sebaceous gland abnormalities.
Key Clinical Applications:
- Canine lamellar ichthyosis
- Cutaneous T-cell lymphoma (epitheliotropic lymphoma)
- Intracutaneous cornifying epitheliomas
- Multiple epidermal inclusion cysts
- Comedo syndrome in Miniature Schnauzers
- Sebaceous adenitis (especially in Standard Poodles and Vizslas)
- Feline acne
Clinical Pearl: Because of its profound effects on sebaceous glands, isotretinoin is often considered the retinoid of choice for sebaceous adenitis and Schnauzer comedo syndrome, whereas other retinoids (like acitretin) might be preferred for primary keratinization defects.
Due to severe teratogenic risks in humans (FDA Category X), obtaining this medication for veterinary use can be highly restricted by manufacturers and distributors.
Mechanism of action
Isotretinoin acts by regulating epithelial cell proliferation and differentiation.
- Receptor Binding: Retinoids enter the cell and bind to intracellular Retinoic Acid Receptors (RARs) and Retinoid X Receptors (RXRs) → altering gene transcription.
- Sebosuppressive Effect: It significantly reduces sebaceous gland size and activity → decreasing sebum production.
- Anti-keratinization & Anti-inflammatory: Normalizes follicular desquamation (preventing comedone formation) and affects monocyte/lymphocyte function, altering cellular immune responses.
- Antimicrobial (Indirect): By altering the microenvironment of the sebaceous pore (reducing sebum), it indirectly reduces bacterial populations.
Safety & warnings
Contraindications
- Pregnancy (absolute contraindication - known teratogen)
- Nursing mothers
- Hypertriglyceridemia
- Severe renal disease
- Severe hepatic disease
- Known hypersensitivity to isotretinoin
Adverse effects
- Dogs: Keratoconjunctivitis sicca (KCS) - most common
- Dogs: GI effects (anorexia, vomiting, diarrhea, abdominal distention)
- Dogs: CNS effects (lassitude, hyperactivity, behavioral changes, collapse)
- Dogs: Stiffness of limbs
- Dogs: Pruritus, exfoliative dermatitis, erythema of feet and mucocutaneous junctions/cheilitis
- Dogs: Polydipsia, swollen tongue
- Cats: Blepharospasm, periocular crusting, erythema
- Cats: Diarrhea
- Cats: Weight loss secondary to anorexia
Precautions
Teratogenicity: Isotretinoin is a known teratogen (FDA Category X). Major anomalies have been reported in children of women taking the medication. It is absolutely contraindicated in pregnant veterinary patients and should NOT be used in households where pregnant women are present.
Hepatic & Lipid Effects: May cause increases in serum triglycerides, cholesterol, and liver enzymes. Use with caution in patients with pre-existing hepatic or lipid disorders.
Ocular Effects: High risk of keratoconjunctivitis sicca (dry eye) in dogs; regular monitoring is required.
Drug interactions
May cause additive toxic effects.
Isotretinoin may increase cyclosporine levels.
Use with tetracyclines may increase the potential for the occurrence of pseudotumor cerebri (cerebral edema and increased CSF pressure).
Monitoring
- Clinical efficacy
- Liver function tests (baseline and if signs appear)
- Serum triglycerides and cholesterol
- Dogs: Schirmer Tear tests (monthly, especially in older dogs to monitor for KCS)
- Cats: Body weight (monitor for anorexia-induced weight loss)
Pharmacokinetics
Absorption
Rapidly absorbed from the gut once the capsule disintegrates. Animal studies show ~25% bioavailability, but food or milk in the gut may increase this amount. Peak absorption may require up to 2 hours.
Distribution
Distributed into many tissues, but is not stored in the liver (unlike vitamin A). Crosses the placenta and is highly bound to plasma proteins. Unknown if it enters milk.
Metabolism
Metabolized in the liver.
Elimination
Excreted in the urine and feces.
Overdose
In a review of 147 exposures reported to the ASPCA APCC (140 dogs, 7 cats), only 5 dogs showed clinical signs, most commonly hypersalivation. Cats showed no clinical signs.
Because of the drug's potential adverse effects, gut emptying should be considered with acute overdoses when warranted. Monitor for GI upset and CNS signs.
Available products
Formulations
- Oral capsules (regular and soft gel)
Human-labeled
- Isotretinoin Oral Capsules: 10 mg, 20 mg, 30 mg & 40 mg (regular & soft gel) (Claravis, Amnesteem, Sotret)
Regulatory status
No regulatory data for: 🇺🇸 US · 🇪🇺 EU · 🇬🇧 UK · 🇭🇰 HK · 🇹🇼 TW · 🇯🇵 JP · 🇰🇷 KR · 🇦🇺 AU
Storage & stability
Capsules should be stored at room temperature in tight, light-resistant containers. The drug is photosensitive and will degrade with light exposure. Expiration dates of 2 years are assigned after manufacture.
Client information
CRITICAL SAFETY WARNING: Isotretinoin causes severe birth defects. Pregnant women, or women who may become pregnant, MUST NOT handle this medication. It is highly advised not to use this drug in households where pregnant women are present.
- Administration: Give this medication consistently either with food/milk or without, as dietary fat significantly increases how much drug is absorbed into the body.
- Sunlight: Avoid prolonged or excessive exposure to sunlight for your pet, as this drug can make the skin more sensitive to UV light.
- Dry Eye in Dogs: This medication frequently causes "dry eye" (decreased tear production) in dogs. Watch for redness, squinting, or thick eye discharge, and expect your vet to perform regular tear tests.
- Cats: Watch closely for loss of appetite and weight loss. If your cat stops eating, contact your veterinarian immediately.
- Cost: Be aware that long-term therapy with this medication can be quite expensive.
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.