DEAR DR. ROACH: What is your take on the benefits versus risks of DMSO? — W.R.

ANSWER: 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 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 an interesting and difficult-to-study compound. It is exceedingly permeable: Within five minutes of being applied to skin, it is detectable in the blood.

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 (where there are other therapies more likely to be effective), given uncertain benefits, I don’t recommend DMSO despite the low risk of harm.