Dimethyl Sulfoxide

Anti-inflammatory, topical analgesic, free radical scavenger Sulfoxide compound

Dosage & Administration Guidelines

Species Route Dose Frequency Duration & Clinical Notes
Dog Topical Apply 10-30% solution or gel to affected area 2-3 times daily Duration: 3-7 days
Notes: Wear gloves when applying; allow to dry before covering.
Dog Intravenous (IV) 0.5-1 g/kg diluted in isotonic fluids Once daily Duration: Up to 3 days
Notes: Use only for severe acute inflammation; monitor for hemolysis.
Cat Topical Apply 10-30% solution or gel to affected area 2-3 times daily Duration: 3-5 days
Notes: Use with caution due to potential for skin irritation.
Horse Topical Apply 90% solution or gel to affected area 2-3 times daily Duration: 3-7 days
Notes: Commonly used as a leg brace; may cause local irritation.
Horse Intravenous (IV) 0.1-1 g/kg diluted in 5% dextrose or saline Once daily Duration: Up to 3 days
Notes: Use with caution; rapid infusion may cause hemolysis.
Cattle Topical Apply 10-20% solution to affected area 2 times daily Duration: 3-5 days
Notes: For udder edema, apply to udder after milking.
Small Ruminants Topical Apply 10-20% solution to affected area 2 times daily Duration: 3-5 days
Notes: Use with caution; may cause skin irritation.

Clinical Indications & Species Uses

General Indications
  • Topical anti-inflammatory
  • Free radical scavenger
  • Drug penetration enhancer
Dog (Canine)
  • Acute musculoskeletal inflammation
  • Traumatic edema
  • Post-surgical swelling
  • Interstitial cystitis (intravesicular administration)
  • Topical adjunct for dermatologic conditions
Cat (Feline)
  • Acute musculoskeletal inflammation
  • Traumatic edema
  • Post-surgical swelling
Horse (Equine)
  • Acute musculoskeletal inflammation
  • Joint swelling
  • Tendonitis
  • Bursitis
  • Equine protozoal myeloencephalitis (adjunctive, controversial)
Cattle (Bovine)
  • Acute musculoskeletal inflammation
  • Mastitis (topical adjunct)
  • Udder edema
Small Ruminants (Sheep / Goat)
  • Acute musculoskeletal inflammation
  • Traumatic edema

Pharmacology & Mechanism of Action

Drug Class: Anti-inflammatory, topical analgesic, free radical scavenger | Pharmacological Group: Sulfoxide compound

Mechanism of Action: Dimethyl sulfoxide (DMSO) is an organosulfur compound with multiple pharmacological actions. Its primary mechanism is the scavenging of hydroxyl radicals, thereby reducing oxidative tissue damage. It also stabilizes cell membranes, reduces platelet aggregation, and has anti-inflammatory effects by inhibiting prostaglandin synthesis and reducing edema. DMSO enhances the penetration of other drugs through biological membranes, acting as a carrier. It also has local analgesic and mild bacteriostatic properties.

Pharmacodynamics: DMSO reduces inflammation and edema by neutralizing free radicals and stabilizing lysosomal membranes. It promotes vasodilation, increases blood flow to the affected area, and has a mild diuretic effect when administered systemically. Its anti-inflammatory action is particularly useful in acute musculoskeletal injuries. DMSO also has cryoprotective properties and is used to protect cells during freezing.

⚑ Pharmacokinetics Summary

Absorption: DMSO is rapidly absorbed through intact skin and mucous membranes. After topical application, peak plasma concentrations occur within 4-8 hours. Oral absorption is also rapid, with peak levels in 2-4 hours. Intravenous administration results in immediate high plasma levels.
Distribution: DMSO distributes widely throughout the body, including the central nervous system, due to its small molecular size and ability to cross biological membranes. It accumulates in tissues with high water content and is concentrated in the skin, muscles, and joints. It crosses the placenta and is excreted in milk.
Metabolism: DMSO is partially oxidized to dimethyl sulfone (DMSO2) and reduced to dimethyl sulfide (DMS). The metabolism occurs in the liver and other tissues. DMS is responsible for the characteristic garlic-like odor on the breath and skin.
Excretion: DMSO and its metabolites are excreted primarily in the urine, with small amounts in feces and exhaled air. The elimination half-life is approximately 11-14 hours in dogs, but may be longer in other species.
Half-Life: Dogs: 11-14 hours; Horses: approximately 10 hours; Humans: 11-14 hours
Bioavailability: Topical: 40-60% (variable); Oral: ~70-80%; IV: 100%
Protein Binding: Low (approximately 10-20%)

Available Formulations & Strengths

Topical Solution 10%, 20%, 30%, 50%, 90% (Topical)
Topical Gel 10%, 20%, 30% (Topical)
Injectable Solution 100% (for dilution) (IV)

Contraindications & Clinical Warnings

Contraindications:
  • Hypersensitivity to DMSO
  • Severe hepatic or renal disease
  • Pregnancy (especially during organogenesis)
  • Concurrent use with cholinesterase inhibitors
  • Application to broken or irritated skin (may increase systemic absorption)
Warnings & Clinical Precautions:
  • Wear impermeable gloves when applying to avoid skin absorption by the handler.
  • DMSO may cause a garlic-like odor on the breath and skin of treated animals.
  • Use with caution in animals with cardiovascular disease due to potential histamine release.
  • Do not apply to areas with compromised circulation.
  • In food animals, observe withdrawal times; DMSO is not approved for use in food animals in some countries.
  • DMSO can enhance the absorption of other topically applied drugs; be aware of potential toxicity.

Adverse Effects & Reactions

Common:

  • Local skin irritation
  • Erythema
  • Pruritus
  • Garlic-like odor on breath and skin
  • Transient burning sensation on application

Serious / Severe:

  • Hemolysis (with rapid IV administration)
  • Renal damage (with high systemic doses)
  • Anaphylactoid reactions
  • Hepatotoxicity (rare)
  • Cataracts (with chronic high-dose use)

Rare:

  • Contact dermatitis
  • Urticaria
  • Methemoglobinemia
  • Neurotoxicity (with high IV doses)

Key Drug Interactions

Interacting Drug / Class Clinical Effect & Mechanism Severity
Corticosteroids DMSO may increase the penetration and systemic absorption of topical corticosteroids, potentially enhancing their effects and side effects. Moderate
NSAIDs DMSO may increase the absorption of topically applied NSAIDs, leading to higher systemic levels and increased risk of GI ulceration. Moderate
Cholinesterase inhibitors (e.g., neostigmine) DMSO may potentiate the effects of cholinesterase inhibitors, leading to excessive cholinergic stimulation. High
Insulin DMSO may enhance the absorption of insulin when applied topically, potentially causing hypoglycemia. Moderate
Sulfonamides DMSO may increase the absorption and toxicity of sulfonamides. Moderate

Overdose & Toxicity Management

Signs of Toxicity:

  • Hemolysis
  • Hemoglobinuria
  • Renal failure
  • Hypotension
  • Tachypnea
  • CNS depression
  • Seizures (with massive IV doses)

Emergency Treatment Protocol: Discontinue DMSO immediately. Provide supportive care: IV fluids to maintain renal perfusion and promote diuresis. Monitor renal function and hematocrit. In cases of severe hemolysis, consider blood transfusion. Administer oxygen if respiratory distress occurs. There is no specific antidote.

Food Animal Withdrawal Times

πŸ₯© Meat: 30 daysπŸ₯› Milk: 7 days

DMSO is not approved for use in food animals in the US; extra-label use requires extended withdrawal times. Consult regulatory authorities for specific guidance.

Storage, Handling & Regulatory Information

Storage Temperature: Store at room temperature (15-30Β°C)

Handling & Special Conditions: Keep container tightly closed. Avoid freezing. Store away from incompatible materials (strong oxidizers).

Dispensing Status: Prescription Required (Rx Only)

Approval Status: Approved for topical use in horses and dogs (e.g., DMSO Gel 90% for horses).

Extra-Label (Off-Label) Use: In the US, DMSO is approved for topical use in horses and dogs for acute musculoskeletal inflammation. Extra-label use in other species or routes requires a valid veterinarian-client-patient relationship and adherence to AMDUCA regulations. For food animals, extra-label use is prohibited if an approved drug is available.

Clinical Pearls & Practice Notes

πŸ’‘ Clinical Insights: DMSO is a versatile agent used primarily for its anti-inflammatory and free radical scavenging properties. It is most effective when applied topically to acute musculoskeletal injuries, but its use is limited by local irritation and the potential for systemic absorption. When using DMSO, always wear gloves to prevent self-exposure. It is important to note that DMSO can enhance the absorption of other drugs, so caution is advised when combining with other topical agents. Systemic use (IV) is reserved for severe cases and requires careful monitoring for hemolysis. In food animals, DMSO is not approved, and withdrawal times must be extended. Overall, DMSO is a valuable adjunct in managing acute inflammation, but its use should be tailored to the individual case and species.

References & Literature

  • πŸ“š Plumb's Veterinary Drug Handbook
  • πŸ“š Papich Veterinary Pharmacology and Therapeutics
  • πŸ“š Compendium of Veterinary Products (CVP)