The side effects of being unique

Every drug ever discovered has side effects. That’s a commonplace, or at least it should be. But it immediately brings up the important questions of how severe those side effects might be and how often they occur under normal usage. Drug developers speak of a therapeutic window between the effective dose and the higher doses that are more likely to bring on trouble. Anything is trouble at a high enough dose, of course: water itself is deadly if you drink an insane amount of it in a short time. But ideally, you want a nice large gap between what a patient is likely to take and any kind of toxic dosage. In case you’re wondering, the most common drug with a narrow window is paracetamol, overdoses of which account for most of the acute liver failures in the Western world, particularly when combined with alcohol.

But what about side effects at the normal doses themselves? This becomes a job for statistics, because the more people who take a given medicine, the greater the chance that someone will have a bad reaction to it. These can range from headaches or a short-lived skin rash all the way up to extremely serious conditions such as anaphylactic shock, and as you would imagine, drug companies are rather keen to know about how common such things might be. But that’s hard-won knowledge in many cases. The word pharmacovigilance covers the process of watching for such things after a new therapy is approved, and it can be hard on the nerves.