It’s a carrier. It introduces whatever is in it to your bloodstream.
Unrelatedly, microwave assisted reactions in DMSO solvent wete found to have some totally gross failure modes that were a pain to clean up and got banned in the lab
Was thought for a while to have anti-inflammatory effects itself.
Ethanol works as an absorption enhancer too.
I once had a long-running (weeks) experiment that used DMSO as a solvent. Early on it was realized that the DMSO was degrading all non-glass rubbers and plastics in the chemical "circuit", which began to sag like an old TinkerToy structure. Had to rebuild/rerun with parts that were resistant to DMSO.
In this incredibly dilute state, the previous mixture of molecules now spreads out and gets taken up by different tissues. The tissues that take up the compounds depends in the molecular properties of the compound in question, so something like PFAS which are highly lipophilic (iirc) meaning fat soluble, they will be taken up by cells pretty readily as they can easily cross the lipid bilayer membrane but will be stored in adipose tissue and continue impacting those cells and possibly be slowly released over time to impact the organism systemically. This of course will depend on initial dose concentration, duration of exposure, adioposity of the organism, along with a multitude of other factors.
The study of how compounds circulate in this way is a subfield of pharmacology known as Absorption, Distribution, Metabolism, and Excretion (ADME)