Trilostane

What is this medication for?

• Pituitary-dependent and adrenal-dependent hyperadrenocorticism (Cushing's), Alopecia X
• Feline hyperadrenocorticism

How is it given?

Give exactly as your veterinarian prescribed — never change the dose or stop on your own unless your veterinarian has told you to.

• Watch closely in the first 10–14 days for signs of over-suppression (low energy/tiredness, vomiting, inappetence) — these can herald acute hypoadrenocorticism/adrenal tissue death; if suspected, stop the drug and give supplemental glucocorticoids.
• Give with food — improves consistency of absorption.

What if I miss a dose?

• Give it as soon as you remember — unless it is almost time for the next dose (then skip the missed one; never double up).
• Call your clinic if you miss more than one dose in a row.

Side effects — what should I watch for?

Effects listed as common in this handout

• Lethargy, inappetence, vomiting, diarrhea, mild electrolyte changes (Up to 63% of dogs, usually early and self-limiting)
• Generally well tolerated

Worth a phone call to your veterinarian

• Any new symptom that worries you.

⚠️ Contact your veterinarian or an emergency clinic IMMEDIATELY if you notice

• Adrenal tissue death, hypoadrenocorticism, death (Rare but serious — can be irreversible)

Before starting (or refilling), tell your veterinarian if your pet:

• has or has had: Hypersensitivity; do not use in pregnant dogs or animals intended for breeding; renal/hepatic disease
• has or has had: Will not shrink adrenal tumors (adrenals may enlarge during treatment despite clinical improvement)

• is pregnant, nursing, or used for breeding
• is taking any other medications, supplements, or flea/tick products, including:
  • ACE inhibitors, potassium-sparing diuretics (spironolactone), potassium supplements
  • Ketoconazole, mitotane, aminoglutethimide

Storage and handling

Room temperature, tight, light-resistant container. Do not open capsules or divide contents.

Good to know

• Watch closely in the first 10–14 days for signs of over-suppression (low energy/tiredness, vomiting, inappetence) — these can herald acute hypoadrenocorticism/adrenal tissue death; if suspected, stop the drug and give supplemental glucocorticoids.
• Not more effective than mitotane per some clinicians' experience, and can be less predictable — the two remain roughly comparable in survival outcomes but require different monitoring approaches.
• Give with food — improves consistency of absorption.