Claritin (loratadine) is an antihistamine that reduces the effects of natural chemical histamine in the body. Histamine can produce symptoms of sneezing, itching, watery eyes, and runny nose.
Claritin is usually taken once per day.
Side effects may include headache, drowsiness, stomach pain, vomiting, dry mouth or nervousness.
When combined with pseudoephedrine, Claritin is marketed as Claritin-D (for decongestant), which makes it useful for colds as well as allergies, but may be likely ot increase anxiety and insomnia in some patients.
Loratadine was approved by the FDA in 1993, and was available only by prescription until going off-patent in 2002, at which time it was available for sale over the counter from a variety of sources, allowing the price to drop significantly.
This description is adapted from information sources found online, and is in no way meant to replace or substitute for professional medical advice. If you are in pain, or considering taking this or any other medicine, contact your medical professional for assistance rather than using the internet as your sole source of information.
My Personal Experience
Antihistamine medications work best in advance - that is, they don't really do much if your head is already stopped up. You have to take them on an ongoing basis, to keep from getting stopped up, or else it's too late to do much (decongestants, on the other hand, are a different story, for another time).
Unfortunately, since I was on Dilantin for a number of years, and decongestants were a no-no that interfered with the drug, I had no choice: it was antihistamine or nothing. As long as they worked, it was great.
The problem is that as with most proactive devices, it often seemed like they weren't doing anything, and so I decided to stop. When I did, it felt like I had been slammed in the head by a slice of lemon wrapped around a large gold brick and unfortunately it took a while for the pain to subside.
Eventually it did, and my only thought is that the Claritin had something to do with the process - but ultimately I really don't know that for certain.