First of all, buying a supplement at Walgreens, what's the point? The quality will be low because they're not in that business. Second, this amino acid metabolite is usually taken more than once a day. Third, it's not a vitamin -- it's a metabolite of tryptophan, an amino acid, that in combination with B6 and other cofactors makes serotonin. However, I doubt you "know" you're low in serotonin -- almost nobody is. There is no connection between serotonin levels and mental illness -- all we know is that if you can alter the way serotonin works in the brain to make it stronger (antidepressants than target serotonin receptors and prevent the natural breakdown of it) or make more of it more efficiently (5-HTP), it has been shown in some people to improve their mood and decrease anxiety. In others, because everyone is an individual, it does either nothing, makes people more nervous, or, in the case of antidepressants particularly, has a million potential side effects and is very hard to stop taking and may alter the brain permanently. 5-HTP has not been shown to have as many adverse side effects, but do watch for increased nervousness. It won't make you end up in the hospital unless you have an unusual allergic reaction to it. It is a natural substance, and comes from a plant, but obviously in isolated form nothing is completely natural -- you have to engineer it to isolate substances. Whether you can drink on it or not depends on you -- some people can drink moderately while taking antidepressants, and some can't. 5-HTP is a more natural and weaker actor on the brain, and because it is the natural substance the brain is used to if the body doesn't think it's necessary it will just break it down and evacuate it from the body -- something the drugs prevent from happening.