Where to find reasonably priced OTC medicines? (Lima)

Hi,

Maybe I'm missing something, but I am finding that ordinary "over the counter" medicines are very expensive here in Lima. I am also having trouble finding medicines that are common in the US.

The two that I have searched for recently are Benadryl and Visine A (for allergy). I went to several pharmacies looking for Benadryl, giving both the trade name and the generic name. The best I got was an offer of an injectable liquid. I just need pills for occasional allergy relief. (It puts me to sleep, but it is the most effective allergy pill I've found.)

I did buy some Allegra, at about $1.50 a pill, 50% more than at home.

For Visine A, I didn't ask for it by name. I just asked for anti-allergy drops for my eyes. I was offered something that costs S/. 66, and when I expressed dismay at the price, was offered something that costs S/. 46. Forty-six soles is still over $15. Visine A usually costs $8, so we're talking twice the price.

In the US, most large grocery stores have items like Benadryl and Visine, cough syryp, painkillers, etc. at reasonable prices. Is there anything like that here?