Always weigh your risks vs. the benefits

Dear Dr. Roach: What is your take on the benefits versus risks of DMSO? — W.R.

DMSO (dimethyl sulfoxide) has only one use approved by the Food and Drug Administration, in people with interstitial cystitis, where it is directly instilled into the bladder. It is also used (off-label is without official FDA indication) as a recovery treatment when the tube delivering some types of chemotherapy comes out of the vein.

DMSO may have a pain-relieving effect, both topically when applied, as well as in the brain, though the mechanism for this is unclear. DMSO is an antioxidant and opens pores in lipid membranes, but again it’s unclear how this relates to its possible effects on people’s symptoms.

It is a difficult-to-study compound. It is exceedingly permeable: Within five minutes of being applied to skin, it is detectable in the blood. It has a distinct flavor and odor that can be noticed after application, which makes doing a controlled trial difficult; subjects in a study find it very easy to know whether or not they have been given DMSO.

It’s estimated that people have spent billions of dollars on DMSO for other conditions, especially arthritis and inflammatory diseases. However, the evidence that it is effective is poor, largely because of the difficulty in doing good studies on this compound, but also because large-scale studies are expensive and there is little enthusiasm on performing such studies on a cheap compound.

The risks appear to be small. Apart from the taste and smell changes, there are rare reports of allergies, discomfort in the bladder after instillation there and possible damage to the eye lens (at least in animals).

You didn’t tell me what condition you are considering DMSO for, but except in the case of interstitial cystitis given uncertain benefits, I don’t recommend DMSO despite the low risk of harm.