A hot bath is probably the original hydrotherapy treatment, and still the best. But as much as you may already enjoy a hot bath, you may not be tapping its full potential. At its best, a hot bath can be a very powerful tool for healing. But to get the most out of it, a little knowledge is very helpful.

Bathing for relaxation
A hot bath is relaxing. It was the original psychotherapy, and I suspect it is still the best.

Technically speaking, however, hot baths are neurologically stimulating. The sensation of relaxation is an illusion, caused by the need to be still while body temperature is restored to normal. While some people do get drowsy after a hot bath, most remain alert for at least an hour.

The most relaxing baths are actually in lukewarm water. Most people I know still prefer a good hot soak, but your nervous system is the most sedated by a not-so-hot bath. If you are taking a bath to get to sleep, try this kind of bath instead.

Bathing for elimination
You sweat under water. In a very hot bath, oddly enough, you can lose a lot of fluid.

Sweating is an important form of excretion, and many waste metabolites and toxins are removed from the body this way. Exercise is one way to do this. A hot bath is a lot easier — and, in fact, people usually sweat much more in a bath than they ever do when exercising.

Some people will call this “detoxification,” a word that gets thrown around too casually, usually to make something sound more therapeutic than it really is. A good sweat is a good thing, but it isn’t “detoxifying” any more (or any less) than having a bowel movement! It is more level-headed to simply say that it stimulates “elimination” of waste products.

But sweating a lot in a bath also means that you must drink water — before, during and after! This is a vital key that most people miss. If you don’t hydrate, a hot bath may actually be stressful to your system — and I think this is why some people do not like baths. You must replace lost fluids to feel good later.

Baths for relieving muscle aching
Hot baths are good for muscle soreness. I don’t believe there is any “official” scientific reason for this — it’s not exactly a hot target for research dollars. However, I have some ideas …

Systemic heating can do something for muscles that no hot pack can ever do. As good as a nice hot pack can feel, the effect is mainly neurological — heat is soothing to a muscle in distress. A hot bath has this effect also, but it additionally is able to actually increase the temperature inside a hurting muscle without exercising it.


Hot packs cannot increase the heat inside your muscles. The human body is incredibly good at getting rid of heat. When you try to heat a muscle with a hot pack, you end up heating just the superficial blood, which quickly gets pumped away and immediately cooled. It has been shown that local heating never “penetrates” much deeper into the tissue than a centimeter, if that. The only really effective way to heat a specific muscle is by making it work, produce heat from the inside out, metabolically. But often this is not desirable in an injured or very fatigued muscle. So what to do? How to get the benefits of heating? The hot bath may work.

In a hot bath, excess heat has nowhere to go. The body cannot get rid of it, anywhere. The entire system heats up slightly, like a fever. It’s not a lot, but it’s much more than you can manage with a hot pack. And this is probably good for sore muscles in several ways.

Another common idea for bathing is that Epsom salts assist with detoxification and recovery from minor injuries, aches and pain. Do they?

Do epsom salts work?
Almost certainly not. Unfortunately, evidence and careful consideration of the evidence strongly suggests that dissolving Epsom salts — magnesium sulfate heptahydrate — in your bath doesn’t do anything at all except make the water feel kind of silky. It’s a pleasant effect, but not therapeutic, or even cosmetic … just aesthetic!

The skin is almost completely waterproof, and passes no molecules or ions except via pores. Osmotic effect is irrelevant, and magnesium sulfate ions can’t get in. The final word is that “anything is possible,” but the smart money says, “don’t bother!”

Not convinced? Epsom salt baths are discussed in (surprising) detail in the article Reality Check! Don't Bother With Epsom Salt Baths.

Much better for backs
A hot bath is not only a much better choice for the great majority of low back pain than icing — which is usually harmful — soaking in the tub may even be the single best therapy there is for low back pain. Or at least the best bang for your buck!

The great majority of low back pain is muscular in origin. Specifically, the immediate cause of the pain is myofascial trigger points (“knots” in your muscles), which can cause far more grief than most people realize — and yet they are relatively treatable. A little reassurance, rubbing, and a hot bath go a surprisingly long way, even with the most horrendous case of low back pain. And while massage therapy is probably the single most effective therapy for most people, most of the time … a hot bath is pretty effective too, and the price sure