Freely penetrates skin and may carry dissolved chemicals across the skin.

The acute toxicity of DMSO by all routes of exposure is very low. Inhalation of DMSO vapor can cause irritation of the respiratory tract, and at higher concentrations may cause vomiting, chills, headache, and dizziness. The material is only slightly toxic by ingestion and may cause vomiting, abdominal pain, and lethargy. Dimethyl sulfoxide is relatively nontoxic by skin absorption, but can cause itching, scaling, and a transient burning sensation. Dimethyl sulfoxide can increase the tendency for other chemicals to penetrate the skin and so increase their toxic effects. Contact of DMSO liquid with the eyes may cause irritation with redness, pain, and blurred vision.

Chronic exposure to dimethyl sulfoxide can cause damage to the cornea of the eye. Dimethyl sulfoxide has not been found to be carcinogenic or to show reproductive or developmental toxicity in humans.

Combustible when exposed to heat or flame (NFPA rating = 1). Carbon dioxide or dry chemical extinguishers should be used to fight DMSO fires.

DMSO reacts violently with strong oxidizers, many acyl halides, boron hydrides, and alkali metals. DMSO can form explosive mixtures with metal salts of oxoacids (sodium perchlorate, iron(III) nitrate).