Dimethyl sulfoxide: Risk versus benefit

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

DEAR READER » 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, meaning without an official FDA indication) as a recovery treatment when the tube delivering some types of chemotherapy comes out of the vein.

DMSO may have a painrelieving 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. It has a distinct flavor and odor that can be noticed after application to the skin, 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 very 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 (where there are other therapies more likely to be effective), given uncertain benefits, I don’t recommend DMSO despite the low risk of harm.

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