Dexamethasone

Medication Facts

Performance enhancing: Potentially
Total hours to clear: 48-96 plasma/urine
Frequently used: Most Prescribed
ESC ID: DEXAME-0278
Trade names: Decadron
Drug type: Corticosteroid
Plasma half-life · hours: 3 to 5 hrs
Equine dosing: 0.02 to 0.1 mg/kg IV, IM, or PO once daily Consult Veterinarian, consult a licensed veterinarian to discuss treatment options before combining with with corticosteroids, caution using with other substances. **Due to severe contraindictations consult a licensed veterinarian to discuss treatment options before combining with Betamethasone, Dexamethasone, Methylprednisolne, Isoflupredone, Triamcinolone. If switching between these withdrawals must be at least 7 days,
Cmax · peak plasma concentration: 0.7 µg/mL
Tmax · time to peak plasma concentration: 12
ESC concentration guidance: 12hr WD 150 pg/mL and 300 pg/mL (0.15 to 0.30 ng/mL). 72 HRS WD 5 pg/mL
Primary withdrawal · hours: 12
Washout withdrawal · hours: 168
ESC control type: A1 - Generally Controlled - Therapeutic
Medication report required: Generally not required, however understand exceptions.

Uses & side effects

Severe allergies, asthma, heaves, musculoskeletal and neurological inflamation, suppressed immune system

The veterinary label reports laminitis with corticosteroids in horses. Higher-than-recommended doses may cause temporary lethargy. Corticosteroids can mask infection and suppress natural steroid production; late-pregnancy use can precipitate delivery and complications. See the full product label in Government Numbers.

Drug interactions

At 12 HR WD if given standard dose Dex may near maximum efficacy. Its strongly encouraged to avoid severe contraindications and if other meducations are on board observe the 72 hour washout. Combining dexamethasone with other medications in horses carries significant risks, primarily due to overlapping side effects like severe gastric ulcers and fatal electrolyte imbalances. Always consult your equine veterinarian before concurrent administration, as careful monitoring or dosage adjustments are strictly required.High-Risk Drug CombinationsNSAIDs (e.g., Phenylbutazone, Flunixin Meglumine): Never combine corticosteroids with systemic Non-Steroidal Anti-Inflammatory Drugs. This combination drastically increases the risk of severe Equine Gastric Ulcer Syndrome (EGUS) and potential kidney damage.Potassium-Depleting Diuretics (e.g., Furosemide): Using dexamethasone alongside diuretics significantly worsens the loss of electrolytes (like potassium and calcium), leading to dangerous imbalances.Calcium-Containing IV Fluids: Dexamethasone should never be mixed directly into intravenous fluids containing calcium, as it can cause adverse chemical reactions.Antibiotics (e.g., Fluoroquinolones): Administering dexamethasone with medications like enrofloxacin can heighten the risk of tendonitis and tendon rupture in horses.Vaccines: Because dexamethasone is a potent immunosuppressant, it can interfere with the horse's ability to mount a robust immune response, potentially compromising vaccination efficacy.Enzyme-Inducing Drugs (e.g., Phenobarbital, Rifampin): These medications can speed up the liver's metabolism of dexamethasone, causing the steroid to become less effective

Contraindications

Clenbuterol, Salbuterol,& other corticosteroids. Dexamethasone is strictly contraindicated in horses with systemic fungal infections, active viral or bacterial infections without concurrent antimicrobial therapy, and high risk of laminitis.

Products & routes

VetOne Dexamethasone

Injectable solution · 2 mg/mL

IV, IM

Product label / source

Veterinary guidance

Dosing and pharmacokinetic data are sourced from publicly available resources, and accuracy is not guaranteed. The dosing samples provided are for illustrative purposes only and should not be used for actual administration; they assume a single medication is delivered at the correct individual dose. Loading doses, or combinations with other substances to increase efficacy or mask concentration levels, are strictly prohibited. Veterinarians must prescribe all medications and determine appropriate withdrawal times based on the horse's health, administration route, drug strength, and timing. The health of the horse must always take priority over performance.

Medication combinations

Combining certain substances or use of can trigger dangerous interactions or contraindications, posing severe health risks or creating unintended performance-enhancing effects. If a medical treatment causes these interactions or alters performance, the horse must be withdrawn from competition until its system clears, or face an adverse drug test.

Government Numbers

VetOne Dexamethasone Injection, 2 mg/mL: ANADA 200-324. NDC 13985-533-03 (100 mL) and 13985-533-25 (250 mL). Labeler: MWI (Vet One). Identifiers apply to this product, not every dexamethasone formulation. DailyMed label updated July 30, 2024; reviewed September 18, 2026. Full label: https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=846a642a-8844-4a2a-ab13-fcfe9d5b655a

Sanctioning-body comparison

Plasma only. Compare published competition guidance for this medication. ESC guidance remains in Medication Facts above. A dosing guideline, withdrawal recommendation and laboratory detection threshold are different measures.

Sources reviewed September 23, 2026. “Not verified” means a gap in this comparison, not zero tolerance or permission. Doses describe the cited rules; your veterinarian must determine treatment and withdrawal.

Published guidance by organization
Organization	Published dose & route	Plasma concentration	Withdrawal / timing	Control / penalty class
AQHA Show HorsesShow rules · 2026 handbook Conditions & sources Do not combine the regular and emergency regimens. VIO405.12–.12.1 Reviewed 2026-09-23 2026 AQHA Handbook · VIO400–406 Current AQHA rulebook	Up to 1 mg/100 lb per 24 h, IV/IM/oral injectable solution; up to 5 days.	0.5 ng/mL	12 h; emergency hives alternative: 0.5 mg/100 lb IV, 6 h, licensed veterinarian and medication report.	Quantitatively restricted therapeutic.
APHA Paint Show HorsesShow rules · 2026 Rule Book Conditions & sources Separate alternative regimens; not cumulative. SC-085.A.8 Reviewed 2026-09-23 2026 APHA Rule Book · SC-085, pp. 75–80 Current APHA rulebook	Alternatives per 24 h: 2 mg/100 lb IV/IM; 0.5 mg/100 lb IV; or 1 mg/100 lb oral powder. Up to 5 days.	No numeric plasma limit stated in SC-085.A.8.	Oral powder: 6 h. No separate stop time stated for the listed IV/IM alternatives.	Listed permitted therapeutic substance.
ARCI Model RulesRacing model · Rules 15 / UCG 20.0 / CTMS 4.2.1 Conditions & sources These numeric limits and times do not apply to flat/jump racing. ARCI’s flat/jump rules impose a 14-day intra-articular stand-down and prohibit corticosteroid stacking. ARCI model comparison only; no state-specific rule is substituted. Schedule timing is tied to its stated regimen and is not a clearance guarantee. CTMS 4.2.1 corticosteroid note; ARCI-011-020(F); UCG 20.0 PDF p. 24 Reviewed 2026-09-23 ARCI UCG 20.0 · April 2026 ARCI CTMS 4.2.1 · December 2020 ARCI Model Rules 15 · August 2026	0.05 mg/kg IM/IV sodium phosphate or oral dexamethasone — harness only	5 pg/mL — harness only	72 h — harness only	Drug Class 4 · Penalty Class C. Harness-only CTMS threshold and timing.
USEFNational Therapeutic Substance Provisions · 2026 + July amendment Conditions & sources Separate alternatives, not cumulative. Dexamethasone isonicotinate is not interchangeable. GR410.5b; dexamethasone guidelines Reviewed 2026-09-23 2026 USEF Drugs & Medications Guidelines · August 10 update USEF July 27, 2026 update	Alternative regimens: 2 mg/100 lb IV/IM at ≥12 h; 1 mg/100 lb oral powder at ≥12 h; or emergency hives regimen 0.5 mg/100 lb IV at 6–12 h. Up to 5 days.	0.5 ng/mL	12 h normally; 6–12 h hives exception requires licensed veterinarian and MRF.	Restricted therapeutic under GR410.5.