A friend of mine recently got pinkeye. Whenever she put in her eye drops, she noticed a distinct and very unpleasant taste on the back of her tongue. What’s up with that?
Grab a mirror and pull down a little on your lower eyelid. Not far from the inside edge (on the side closest to your nose), you’ll notice a tiny hole. This is the lacrimal punctum. When you produce tears or have another liquid in your eyes, some of it drains into these holes and then into the lacrimal sac, the nasolacrimal duct, and eventually into the back of your nose and throat, where you might get a taste.
This is normal and safe, but eye drops aren’t exactly designed with flavor in mind. You can use a technique called "punctal occlusion" to slow or stop the draining, though. Just press a finger against the bony structure between your eye and the bridge of your nose. This stops up the eye’s drainage pipe and keeps the drops from flowing down into your nose. Keep pressing long enough and the excess liquid will evaporate instead of leaving a funky taste in your mouth. As an added bonus, this keeps the drops on your eye longer to do their job.