I've found little on Pubmed on the topic.
I do take it. First there is published evidence
of a fairly long biological half-life.
7.5 days in one person.
See PMID 10642107
Therefore, I suggest the dose given
by "proponents' should be seen as
an "accumulative loading dose" and at some
point a lower dose is appropriate.
Perhaps around one gram or half a gram.
It can have several side effects especially
at the higher doses. Seems to tend cause leg
and foot cramp/spasms in the morning
at less occassionally.....ouch. I recall this
after taking the larger dose and I cut the dose as
a result. Understand this comment
is based only on the comments one
other man (his comments would mirror mine)
and my experience. I am fully calcium
and magnesium replete as far as I know
so it wasn't that, I don't think. Other, than
that it can change the character of feces by
giving a sulfurous smell and seems to cause
a little flatulence....not alot at the higher doses.

It seemed to help speed the recovery of a back strain,
I got due to lifting a injured person. I haven't gone blind, yet:-)
DMSO is not MSM though some DMSO is
said to be changed into MSM in the body.

MSM aka dimethyl sulfone is found in the bovine
adrenal gland as I recall.

My stomach is NSAID intolerant.
NSAID is short for Non-Steroidial Anti-Inflammatory Drugs,
example of which are Aleve and Ibuprofen.
Over the long term MSM effects are long lasting, whereas,
NSAIDs and tylenol only masks pain for a some hours.

Sometimes MSM is called DMSO2
as it has other oxygen atom in the molecule.

Some suggest that gut flora use it to synthesize
sulfur containing amino acids. Even after I was off MSM,
the back stayed better, whereas, before without MSM use,
the back would flare and hurt for longer period of time in
comparison. It works more slowly than NSAIDs but it
seems to help actual healing; whereas NSAIDs just
ruin your stomach ( and possibly the liver and kidneys)
and mask the problem.

Have you done a Pubmed search?

Did this help?

If you find anything, I'd be interested.

These are just my observations and I can provide
no warrenty of safety.

The physician will offer NSAID for pain.

I will provide a warning
that NSAIDs are common but quite risky drugs.
Repeat after me, "Gastrointestial Bleed" as that
is what NSAIDs carry as a risk. GI bleeds can kill
either by blood loss or by the adverse effects of
a virus carrying blood tranfusion. They also can
cause ulcers which are a special misery all
by themselves. So when the MD offers a prescription
for an NSAIDs be careful and at a minimum insist
on one of the somewhat less risky new generation
NSAIDs.

There maybe little science on MSM but it helps.
It doesn't ruin the stomach like what MD will offer.