A first: a medication with increased tear production as a side effect

[Flick]

The bad news: it's chemotherapy.

I was looking up information about fluorouracil, a chemo drug, for a family friend and found the following under less common side effect:

Increased production of tears. This may sometimes be caused by 5FU. This is a temporary side effect, although the tears can sometimes irritate the front of the eye (conjunctiva). If this happens your doctor can give you soothing eye drops.
http://www.cancerbackup.org.uk/Treat...orouracil#1750

I'm just so used to seeing dry eye as a side effect, it's weird to see the opposite. Also exciting in a way, because maybe scientists will be able to figure out the mechanism by which it increases tears, and this could be isolated and become a new therapy.

[Erik]

We know the mechanism, and it is not actually increased tear production. Certain chemo drugs (5-FU, taxol, docetaxel, abraxane) can cause stenosis of the canalicular ducts, resulting in reduced outflow of tears (kind of like someone who has had all 4 puncta cauterized or plugged). This results in epiphora, or an excess of watery tears, which for most patients is uncomfortable (though a few prefer it to the dryness). I have sents patients to the ophthalmologist to have this process reversed on a number of occasions.

For the skeptics among you, here is an article on the topic.

There are other drugs which increase tears measurably, though only very modestly in most patients: cevimeline (evoxac), pilocarpine, bethanechol. I have tried all of the above, with little or no benefit.