Physicians and pharmacists know that every drug prescribed (and even over-the-counter medications that can be taken without a prescription) has both benefits and side effects.
Some side effects are barely noticeable. We say these are tolerable. Others can cause a wide range of symptoms (e.g., itching, headaches, difficulty breathing, loss of sex drive) that are considered intolerable — the affected patient is either unable or unwilling to suffer those effects.
The goal is to give the patient maximum benefit of the drug with the least amount of side effects. Sometimes medications are given in a standard dose, the effects are observed, and then the dosage and frequency (how often you take it) are tweaked a bit until you get the best response possible for that medication.
Pain relief is usually the main goal. Providing pain relief without affecting function and quality of life because of adverse side effects is the challenge. Often, it’s a wait-and-see approach to pain control knowing that every drug has its benefits and side effects that will become more apparent over time.