Caitlin writes, "Hey Robyn, would you be willing to do a post talking about birchbox advocating the use of citrus fruits on the undereye area? It's in this month's feb teaser..."
If you don't want to watch the whole thing, the offending suggestion takes place at 5:40.
The claim is that lemons are a natural diuretic, and thus that putting lemon juice under your eyes is somehow a good idea for reducing undereye puffiness.
Okay, first of all, what is a diuretic? A diuretic is a substance that increases the production of urine. Typically, they are used to treat serious medical conditions like heart failure or kidney disease. Because the skin around your eyes is very thin, slight differences in fluid levels will affect this area more significantly. The idea, then is that a diuretic will drain the extra fluid in your eye-area, leaving you with model-perfect undereyes.
Lemon juice does indeed have a mild diuretic effect.There are a lot of different diuretic mechanisms and I can't find a reliable source on the mechanism of lemon juice in particular. However, regardless of the specific mechanism, lemon juice's (very, very, very slight) diuretic effect is when consumed. Putting it on your face isn't going to do much of anything.
There are also serious risks to putting citrus on your face. Putting citrus on your face can cause a phototoxic reaction called phytophotodermatitis, an inflammatory reaction that results in bruise-like hyperpigmentation, with the potential for nasty-looking blisters. It's often mistaken for chemical burns. This is not only an ineffective treatment for undereye bags, it is downright dangerous.
I'm guessing that Birchbox made this video using the assumption that lemons are natural and therefore can't be harmful. Remember, though, to do your research before sticking random crap on your face.