Read the product labels
When choosing an over-the-counter (OTC) drug, know what ingredients are in the product and what those ingredients do.
A drug that is marketed for cold and sinus symptoms may contain exactly the same ingredients as another marketed for allergy symptoms. Know what ingredients your medicine should have. This is especially important with combination drugs that are designed to treat a variety of symptoms. Check all the ingredients, so that you don't unintentionally take a double dose of one ingredient that is present in two different drugs you're taking.
Consider generic drugs
Again, read the product labels. Generic OTC drugs usually contain the same ingredients as the corresponding brand name products, but are typically much less expensive. If the ingredients are the same, both products will be equally as effective.
Don't forget dosage
In addition to looking at the ingredients listed on a label, check the amount of each ingredient included in the drug. Quite often, the "Extra Strength" version of an OTC medication just includes more of the active ingredient.
Be aware of drug interactions.
If you are already taking one drug, make sure it is safe for you to take another drug at the same time. Most drug labels come with warnings about possible drug interactions. If you're not sure, ask the pharmacist.
Be aware of any special conditions you have.
For example, people who have high blood pressure or heart problems should not use a decongestant that contains pseudoephedrine. Women who are pregnant or breastfeeding should consult their doctor.
When in doubt, check with your doctor
If you are unsure if a drug is appropriate for you, contact your doctor. This is particularly important for patients with certain medical conditions or who are taking certain prescription drugs.