Drugs
One of the biggest jokes in medicine is the way people talk about "therapeutic effects" and "side effects."
If you step back and look at it objectively through the lens of symmetry, you realize that every substance we put into our body simply has effects.
Whether we describe an effect as therapeutic or as a side effect is largely a matter of narrative and context.
In fact, there are drugs where what is normally described as a side effect becomes the desired outcome. For example, SSRIs often inhibit sexual function. For someone taking them to treat depression, that may be considered an unwanted side effect. But the very same effect can be used to treat premature ejaculation, in which case it suddenly becomes the therapeutic effect.
The drug itself hasn't changed. Only our objective has.
Every substance we place into our body has a range of effects.
Food is medicine. In the healthcare of the future we should be able to measure which comes in and everything which comes out of our bodies and adjust according to the needs of our body as a system.
What is our fundamental constraint at any given time for our health?
Drugs can be very useful tools if they hit an immediate constraint.