Well, I had to start researching because I was curious...

The main active ingredient in all formulas of Pamprin and Midol (but 2, oddly enough, Midol Liquid Gels and Midol Extended Relief) is acetaminophen, aka the name brand Tylenol. The amount per dose is different based on the formula and other active ingredients, too.

Some versions have caffeine (diuretic) or pamabrom (another diuretic I have never heard of); aspirin (pain reliever, of course); giphenhydramine citrate (sleep aid) in their pm formula; and an antihistamine to "help relieve swelling due to water-retention during your menstrual period." in Midol's Complete formula. (I take Zyrtec, an antihistamine, every day for my allergies but still swell a lot during my period due to water retention, so I have no idea where they can up with that??)

Midol Liquid-Gels is 200 mg of ibuprofen per capsule.

Midol Extended Relief is Naproxen Sodium (aka, Aleve)...200 mg per capsule.

And Motrin is a name brand of ibuprofen, p.s.

http://midol.com/products.html

http://www.pamprin.com/drug-facts/index.html