Description: well, in its ‘natural’ form Geriatricol is a swarm of self-replicating nanobots that are individually too small to see. But in its natural form Geriatricol will self-destruct when exposed to atmosphere, so it usually comes in the form of a yellow gel pill.
Powers: one dose of Geriatricol cosmetically ages the subject. Within five minutes of ingestion, his or her skin and hair will wrinkle and whiten; sweat, stools, and urine will become compatible with an old person’s; and a superficial blood analysis will bring back a positive result for a number of minor ailments associated with being old. The effects are not permanent: if not reversed, the process begins to reverse itself within two weeks and completely reverse within two more. Underlying health, reflexes, mental agility, bodily functions, and ultimate lifespan remain unaffected.
Geriatricol is, of course, an espionage tool. It’s faster than a disguise kit (even a hyper-tech disguise kit) and more reliable, too: the nanotech is comprehensive enough to fool a routine medical scan and it lacks serious side effects. It won’t fool a thorough medical scan, though — or at least a thorough medical scan that can detect nanotechnology. Advanced societies know about the nanotech’s existence, and know how to check for it; but somebody dosed with Geriatricol can still con their way through a security checkpoint with some applied social engineering. Assuming, of course, that old age is even a thing in those cultures in the first place (it often is, alas).
Less technologically advanced societies will be at a distinct disadvantage.
All in all, Geriatricol is very useful when spying on primitive cultures. There’s just something about having authentically old skin and hair when it comes to being underestimated — or better, not being really noticed at all. Particularly since Geriatricol does nothing to hinder somebody’s combat abilities, which can come as a painful surprise to somebody who just tried to mug the wrong old person.