Dimethyl Sulfoxide (DMSO)
Sulphinylbismethane
Also known as: Domoso · Kemsol · Rheumabene · Synotic · Rimso-50 · DMSO · dimethyl sulphoxide · dimethylis sulfoxidum · NSC-763 · SQ-9453 · Dimethyl sulfoxide
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 |
|---|---|---|---|---|---|
| Acute swelling due to trauma | Liberal application should be administered topically to the skin over the affected area 3-4 times daily. Total daily dosage should not exceed 20 grams (or mL of liquid) | topical | q6-8h | Max 14 days | 🌎 NA |
| Calcinosis cutis | Apply topically to a small area of the body initially (if extensive areas are involved) once daily; and as these areas improve, add new treatment areas. | topical | q24h | — | 🌎 NA |
| Persistent cases of hemorrhagic cystitis (secondary to cyclophosphamide tx) | 10 mL of DMSO medical grade 50% solution is diluted with 10 mL of water and instilled into bladder and removed after 20 minutes. | intravesical | once | 20 minutes | 🌎 NA |
| Extravasation of cytotoxic vesicant (e.g., doxorubicin) | Dose not specified in monograph; apply to affected area | topical | Not specified | Not specified | 🌍 EU |
| Haemorrhagic cystitis induced by cyclophosphamide | Dose not specified in monograph | Intravesical | Not specified | Not specified | 🌍 EU |
| Canine calcinosis cutis | Dose not specified in monograph | topical | Not specified | Not specified | 🌍 EU |
| Renal amyloidosis | Dose not specified in monograph | PO/IV/SC | Not specified | Not specified | 🌍 EU |
- Calcinosis cutis: Dogs may 'feel bad' if large areas are treated initially, but do not become hypercalcemic.
- Extravasation of cytotoxic vesicant (e.g., doxorubicin): Wear gloves during application.
- Haemorrhagic cystitis induced by cyclophosphamide: Instilled directly into the bladder.
- Canine calcinosis cutis: Anecdotal evidence. Monitor serum calcium due to risk of renal calcification.
- Renal amyloidosis: Efficacy is unproven.
Cats
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| Extravasation of cytotoxic vesicant | Dose not specified in monograph; apply to affected area | topical | Not specified | Not specified | 🌍 EU |
- Extravasation of cytotoxic vesicant: Wear gloves during application.
Horses
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| Acute swelling due to trauma | Liberal application should be administered topically to the skin over the affected area 2-3 times daily. Total daily dosage should not exceed 100 grams (or mL of liquid) | topical | q8-12h | Max 30 days | 🌎 NA |
| Adjunctive treatment with surgical colics | 25 mg/kg IV intraoperatively and continued twice daily for the first 24-48 hours post-op. | IV | q12h | 24-48 hours | 🌎 NA |
| Acute rhabdomyolysis | 1 g/kg in a 10% solution of lactated Ringer's or Multisol IV or orally. | IV/PO | once | — | 🌎 NA |
| Adjunctive treatment for laminitis | 0.1-1 g/kg IV, 2-3 times daily | IV | q8-12h | — | 🌎 NA |
- Adjunctive treatment with surgical colics: Administer slowly at 10% concentration.
- Acute rhabdomyolysis: May be given in the acute stages once hydration status has been restored.
- Adjunctive treatment for laminitis: Administer slowly at 10% concentration.
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Overview
Dimethyl Sulfoxide (DMSO) is a highly versatile, dipolar, aprotic solvent with unique pharmacological properties. It is primarily utilized in veterinary medicine as a free radical scavenger and topical anti-inflammatory agent.
- Primary Approved Use: FDA-approved as a topical application to reduce acute swelling due to trauma in dogs and horses.
- Off-Label Uses: Adjunctive treatment for CNS trauma, cerebral edema, transient ischemic conditions, skin ulcers, burns, intestinal surgeries, amyloidosis, and limitation of tissue damage following chemotherapeutic extravasation (e.g., doxorubicin).
- Penetration Enhancer: DMSO easily penetrates intact skin and biological membranes without causing irreversible damage. It acts as a powerful carrier agent, promoting the percutaneous absorption of other drugs (e.g., corticosteroids, antibiotics, analgesics) and potentially toxic compounds.
- Clinical Pearls: Because it is extremely hygroscopic, it will self-dilute if left exposed to room air. Medical-grade DMSO must be used to avoid carrying industrial impurities into the systemic circulation.
Mechanism of action
DMSO exhibits a diverse array of pharmacological effects through multiple pathways:
- Free Radical Scavenging: DMSO directly traps the free radical hydroxide (OH•), while its primary metabolite, dimethyl sulfide (DMS), traps free radical oxygen. This mechanism underpins its anti-inflammatory, cryopreservative, anti-ischemic, and radioprotective qualities.
- Enzyme Inhibition: Inhibits alcohol dehydrogenase → slows the metabolism of alcohol and prevents the conversion of ethylene glycol into its toxic metabolites (making it a potential, though less common, antidote for antifreeze toxicity).
- Prostaglandin Modulation: Enhances Prostaglandin E (PGE) but blocks the synthesis of PGE2, PGF2-alpha, PGH2, and PGG2, contributing to its analgesic and anti-inflammatory effects.
- Vascular Effects: Provokes histamine release from mast cells → local vasodilation. It also decreases platelet aggregation.
- Neuromuscular: Exhibits weak anticholinesterase activity.
Safety & warnings
Contraindications
- Mastocytomas (due to mast cell degranulation)
- Dehydration or shock (diuretic and vasodilatory effects may exacerbate)
- Pregnancy (teratogenic at high doses in some species; use with extreme caution)
Adverse effects
- Local 'burning', erythema, vesiculation, and dry skin (topical)
- Garlic or oyster-like breath odor
- Lenticular changes (myopia) with chronic high doses
- Hemolysis and hemoglobinuria (IV in horses, especially at >10% concentration or rapid administration)
- Diarrhea, muscle tremors, and colic (IV in horses)
- Rare hepatotoxicity and renal toxicity
Precautions
Handling Warning: Always wear rubber gloves when applying topically. Apply with clean or sterile cotton to clean, dry skin to prevent carrying harmful impurities or environmental toxins into the systemic circulation.
- Masking Pathology: Potent anti-inflammatory and analgesic activity may mask existing pathology.
- IV Administration: In horses, administer IV slowly and at concentrations of 10% (maximum 20%) to minimize hemolysis and hemoglobinuria.
- Odor: Owners should be warned about the strong garlic/oyster breath odor that develops shortly after administration, regardless of route.
Drug interactions
Avoid concurrent use due to DMSO's anticholinesterase activity.
Can cause fatal mercury intoxication if mixed and applied topically.
DMSO inhibits alcohol dehydrogenase and may prolong the effects of alcohol.
May be potentiated by DMSO.
May be potentiated by DMSO.
May be potentiated by DMSO.
Profound enhancement of systemic absorption of the co-administered substance, potentially leading to systemic toxicity.
DMSO may decrease the activity and efficacy of dexrazoxane; concurrent use should be discouraged.
Monitoring
- Clinical efficacy (reduction in swelling/inflammation)
- Hemoglobinuria and hematocrit (especially in horses receiving IV therapy)
- Ophthalmic exams (with high doses or chronic use in dogs to monitor for lenticular changes)
Pharmacokinetics
Half-life
Absorption
Well absorbed after topical administration, especially at concentrations between 80-100%.
Distribution
Extensively and rapidly distributed to virtually every area of the body.
Metabolism
Metabolized to dimethyl sulfide (DMS).
Elimination
Primarily excreted by the kidneys, although biliary and respiratory excretion also takes place. Rapidly eliminated in cattle (no detectable drug/metabolites after 20 days).
Overdose
The reported LD50 following IV dosage is approximately 4 g/kg in cats and 2.5 g/kg in dogs.
Clinical Signs of Toxicity:
- Non-lethal doses: Sedation and hematuria.
- Higher dosages: Coma, seizures, opisthotonus, dyspnea, and pulmonary edema.
Treatment: Should an acute overdosage be encountered, treat supportively.
Available products
Formulations
- Topical Gel (90%)
- Topical Solution (90%)
- Aqueous Solution (50%)
- Otic Solution (60% with fluocinolone)
Veterinary
- Domoso® Gel 90% (60 g, 120 g, 425 g)
- Domoso® Solution 90% (1 pint, 1 gallon)
- Synotic® Otic Solution (DMSO 60% + fluocinolone acetonide 0.01%)
Human-labeled
- Rimso-50® (50% aqueous solution in 50 mL)
Regulatory status
POM (Prescription Only Medicine)
POM-V (Prescription Only Medicine - Veterinarian)
No regulatory data for: 🇺🇸 US · 🇭🇰 HK · 🇹🇼 TW · 🇯🇵 JP · 🇰🇷 KR · 🇦🇺 AU
Storage & stability
Must be stored in airtight containers away from light. Store in glass or in the original manufacturer's plastic container (DMSO reacts with some plastics). If exposed to room air, it will self-dilute to a concentration of 66-67% due to its hygroscopic nature.
Client information
Important Safety Guidelines for Pet Owners:
- Use Only Prescribed Medical Grade: Never use industrial or non-medical grades of DMSO (often found in hardware stores), as they may contain harmful impurities that the DMSO will carry directly into your pet's bloodstream.
- Protect Yourself: Always wear rubber gloves when applying this medication. If it gets on your skin, you will absorb it and likely taste garlic in your mouth shortly after!
- Application: Apply only to clean, dry skin using clean or sterile cotton. Do not mix with any other ointments, flea products, or chemicals without your veterinarian's explicit approval, as DMSO will pull those chemicals into the body.
- Odor: It is completely normal for your pet to develop a strong garlic or oyster-like breath odor while on this medication. This will resolve once the medication is stopped.
- Storage & Handling: Use in a well-ventilated area. Avoid inhaling it or getting it in your eyes. It may damage certain fabrics. Keep the lid tightly closed when not in use, as it pulls moisture from the air and will dilute itself. Keep out of reach of children.
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.