Other than surgery, drugs are mainstays of disease therapy. We take chemicals to treat ourselves, but why is that? Why chemical, as opposed to light, ultrasound, electricity, odors, or some other type of intervention? The reason is that plants, from which most of our drugs come, have spent millions of years engaged in medicinal chemistry, and have created some of the most potent biological molecules.

But there are exceptions. For example, one group at Harvard recently published that exposing mice to flashing lights cleared beta amyloid plaque in the brain. This was likely because the flashing light drove gamma oscillations in the brain.

But it’s worth taking a moment to think about what non-chemical therapies work.

Let’s start with light therapy.

Psoriasis is treated with ultraviolet light, typically in conjuction with a chemical called psoralen that sensitizes the skin to UV light. (The chemical is a natural product, by the way, found among plants, in celery, which is why you can get a really bad sunburn if you walk around in the sun after eating a lot of celery.)

Staying with electromagnetic energy, let’s next look at electrical therapy.

Most of us are familiar with electrical stimulators that are used to fix heart rhythm, such as pacemakers, but electrical stimulators are also used for treatment of depression and seizures. Some recent data suggests that vagal stimulaotr can help treat autoimmune conditions such as rheumatoid arthritis, and diabetes. There are some startups trying to use stimulators for obesity.

But there are some unusual therapies. For example, Optune is a a cap that uses electrical fields to slow down the growth of brain tumors. Yes, it’s FDA approved. This is to be distinguished from the caps that use cold water to prevent hair loss during chemotherapy.

Moving onto the infrared part of the electromagnetic spectrum, let’s turn next to heat and lack thereof.

Heat has been used for a long time to treat abscesses, of course.

But what about Coolsculpt? Invented by a dermatologist who had a condition called popsicle panniculitis as a child, it is used to reduce fat. Popsicle pannisulitis are dimples that children cometime get when they eat too many popsicles. The popsicles make the fat cells in the cheeks die and it results in a dimple.

Of course, there is also phototherapy for seasonal affective disorder, for depression, for prevention of nearsightedness, etc. I haven’t seen temperature therapy for circadian rhythm disorders, but given the evidence that slow temperature fluctuations affect circadian rhythm, I wouldn’t be surprised if one day someone tried it.

And then, some other types of therapies.

Another is ultrasound, used to break apart kidney stones and gallstones. But more than that, recently, a new therapy uses ultrasonic waves to heat and destroy a part of the brain called the thalamus, to treat tremors. And yes, that is approved by the FDA. Transcranial magnetic stimulation for treatment of depression and transcranial electrical stimulation for depression and pain are also approved by the FDA and/or EMA.

Hyperbaric therapy is effective for compression sickness. It also seems to works for wound healing. There have been efforts to lower core temperature, or hypothermic therapy, for strokes, where it didn’t work, but is used sometimes in cardiac patients.

For cats, there is pheromone therapy, (which is not FDA approved by the way), to control behavior.

And finally, there is of course organisms. Probiotics. Fecal transplants.