The ideas “therapeutic effect” and “side effect” are opposite concepts in medicine. A drug’s therapeutic effect is a desired effect for treating a disease, while a drug’s side effect is an undesired effect on the patient.

For example, the therapeutic effect of Tylenol #3 is to ease pain, and the side effect is to cause constipation. Although we can separate a drug’s effects as being either therapeutic or side effects, we cannot physically separate the drug into two such portions. When we use Tylenol #3 to treat a patient, these two opposite effects are always bound together and cannot be separated, even though we can cut the tablet into two, three, four, or a hundred parts.

There is, in fact, no difference between therapeutic and side effects; both are effects of the drug. But we separate the effects into two groups so that we can compare the opposing actions of the drug. Tylenol #3 is made of codeine and acetaminophen, not of a “therapeutic” portion and a “side effect” portion.

We tend to think of side effects only in relation to chemical drugs, but this is not the case. Many people believe that food grown naturally and organically must be totally healthy. However, everything in the universe has two opposite sides; both the desirable and the undesirable effects are part of the total package. Even water – the source of all life on earth – can have an undesirable effect: while large amounts of water can save a dehydrated patient, too much water in some cases can lead to water poisoning.

To benefit most from the therapeutic effects and minimize the side effects of a drug, proper timing is required. Using our original example, although Tylenol #3’s therapeutic effect is to lessen pain and its side effect is constipation, a doctor may well prescribe it to a patient who suffers from chronic diarrhoea. It’s not that the Tylenol has changed, but rather that its side effect, which is normally undesired, has now become the desired therapeutic effect. The difference is in the timing.

The same applies to food. If we eat foods in the wrong season, we have a higher chance of experiencing undesirable effects from them. For example, if we eat watermelon on a hot summer day, it can help us weather the heat, but if we eat the same watermelon on a cold winter day, it is likely to cause indigestion and stomach cramps.

The ancient Chinese discovered long ago that timing is critically important when choosing food and medicine. They believed in eating according to the seasons to maintain health, because then we benefit most from the food’s desirable effects and lessen the impact of the undesirable effects.

–Dr. Thomas Zhang