It all goes to show how people are affected in different ways by this illness. I haven't been able to drink alcohol for years and years and I miss it badly!
It would be interesting to find out if those who suffer from heat fatigue are the same ones who can't tolerate alcohol....I can't take the heat or hot showers either.
Many neurological illnesses are caused by toxins (i.e. poison in the blood). Inflammation or damage to nerves often occurs as a result of toxins in the bloodstream, e.g diabetic neuropathy is causd by faulty metabolism which results in an excess of sugar (excess sugar is toxic to nerves).
Apparently, alcohol is one of the most poisonous things we ever put into our bodies. It's fine for healthy people because the liver can usually handle it, but not if it is being chronically overworked by other poisons the rest of the time. There's a great article on alcohol here
Once in the body, alcohol is quickly converted to acetaldehyde which is approximately 30 times more toxic than alcohol. Acetaldehyde is responsible for the unpleasant side effects after drinking.
Autoimmune activity still gets the most of the blame for the neurological damge in MS, as it does in peripheral neuropathy disease, but I'm always open to the idea that some kind of 'hard to identify/detect' toxin (or food allergen) is stealthily triggering the damage or autoimmune response. It could be a viral toxin, mercury or toxin from candida fermentation (also acetaldehyde).
Sorry to ramble on but any sudden excess of toxins, like drinking alcohol, is bound to temporarily make MS symptoms worse.