Contrary to popular belief, antibiotics won’t do anything for a cold or the flu, since they’re caused by viruses and not bacteria. Your best bet is to just treat the symptoms and let it pass through your system. The best way to do that is to stay hydrated and get plenty of rest. If that’s not proactive enough for you, cold medicine might be able to help.

There are three major categories of cold medicine: decongestants, cough suppressants, and expectorants. Some of the most popular brands combine two or more of these actions for multi-symptom relief. Look at the bottles before you buy; it’s important to know which mechanism may help your symptoms.

NOTE: If your cough lasts several weeks, you have a fever of 101°F or higher, you’re coughing up thick yellow or green phlegm (or blood), or you’re wheezing, it’s time to put down the Robitussin and call a doctor.

DECONGESTANTS (SUDAFED)

Decongestants work by reducing inflammation in your nose and airways, thus making it easier for you to breathe.

Good for: Stuffy nose and other congestion in the upper respiratory tract (your face and neck)

Won’t help with: Cough, runny nose

Watch out for: Do not take a decongestant for more than three days. If you do, you might experience a rebound effect, which can make you more congested than you were to begin with.

COUGH SUPPRESSANTS (HALLS, DELSYM, ROBITUSSIN DM)

Cough suppressants work by shutting down your cough reflex. This may seem like a good thing, especially if you’ve been hacking for days, but coughing is your body’s way of trying to get rid of gross stuff in your chest and throat. There’s also very little evidence that cough suppressants actually work (although there’s also little evidence that they don’t work).

Good for: Possibly repressing coughs so you can sleep

Won’t help with: Nasal congestion, actually beating a cold

Watch out for: Many cough suppressants contain an additive called dextromethorphan (the “DM” in Robitussin DM) that can speed up your heart rate. If you’ve had any heart problems or high blood pressure, do not take these drugs before talking to your doctor.

EXPECTORANTS (MUCINEX)

It’s right there in the name: Expectorants help thin the gunk in your body so you can cough it up and spit it out. Drinking water can also help with this.

Good for: A chest full of phlegm

Not great for: Anybody working in close quarters—the results are going to be rather visceral

Watch out for: Like cough suppressants, there’s little evidence that expectorants actually help. Pay attention to your cough. If you feel like the medicine isn’t helping, there’s no reason to keep taking it.

All photos courtesy of iStock.