From the MSDS of DMSO:
Causes irritation to skin. Symptoms include redness, itching, and pain. May cause scaling, Readily absorbed through the skin. Garlic-like taste and odor may develop on the breath and skin. Transient disturbances of color vision, photophobia, headache, diarrhea, and dermatitis may result from skin applications. A good solvent; may result in the increased skin absorption of other more toxic materials.
Absorption may affect the blood, Repeated skin application may cause scaling dermatitis. Repeated oral doses may effect the liver and kidneys.
11. Toxicological Information
Oral rat LD50: 14,500 mg/Kg. Irritation data (std Draize, rabbit): Skin = 500 mg/24 hour, mild; Eye = 500 mg/24 hour, mild. Investigated as a tumorigen, mutagen, reproductive effector.