(WECT) - Every day millions of Americans reach for over-the-counter pain killers, and though many of the drugs treat similar symptoms they don't all work the same way.
"One medication may work just fine for one person but it may not work at all for someone else," said emergency physician Dr. Reza Tigari. "Or it may actually cause side effects that are undesirable in some people."
Of the choices there are three major groups: acetaminophen, sold under the brand name Tylenol; ibuprofen, with brand names like Advil and Motrin; and aspirin.
Because there is no way to tell which one will work best for you, doctors recommend starting with acetaminophen because it has the lowest risk of side effects.
"For a simple, normal headache that's mild to moderate, Tylenol works fine," said Dr. Tigari.
Acetaminophen passes through the liver so don't drink alcohol while taking it, and don't take it if you have a liver disease - an overdose can be serious.
If you don't have success with acetaminophen, try ibuprofen. If your injury involves pain and swelling, the anti-inflammatory may do the trick. Doctors say reducing inflammation is a key component of pain reduction.
Doctors recommend taking ibuprofen with food.
Aspirin is the last choice because it's the painkiller with the greatest risk of side effects and can cause bleeding ulcers.
With any over the counter medication, how much and how often you take them is also a concern.
"When you take them too much. When you take them for too long. When you take doses that are inappropriately high, that's when you run the risk of side effects," said Dr. Tigari.
Doctors say it's especially important to talk with your physician if you have a pre-existing health condition.
If you're looking to save some money, Dr. Tigari says to buy the generic brands of the medications. It's the same drug and will cost you less.