Why Does Cold Medicine Make Me Drowsy?

There are two main reasons cold medicines might make you drowsy. One is that one or more ingredients in the medicine may cause drowsiness. The second reason is that an ingredient in the cold medicine could be interacting with another medicine you take, which could cause drowsiness. First, let’s look at ingredients typically found in cold medicines.

Ingredients that May Cause Drowsiness

Not all labels say “drowsy” or “non-drowsy,” so we want to give you some more information that can help you find a non-drowsy cold medicine. It’s important to choose cold medicine with only the ingredients you need. This can help avoid unwanted side effects such as drowsiness. You should also know that, usually, medicines labeled “nighttime” are formulated to help you sleep.

Pain/fever relievers

Most cold and flu medicines sold in stores contain aspirin, acetaminophen or ibuprofen. These ingredients serve a double duty. They all can relieve pain associated with cold and flu, like headaches and body aches, and they can help reduce a fever as well. None of these ingredients has sleep-inducing properties.


Since the main symptom of a cold is congestion in your nose and/or chest, cold medicines usually contain a decongestant ingredient. Examples include phenylephrine and pseudoephedrine. These typically do not cause drowsiness and can make some people feel hyper or more alert.


Some cold medicines, especially those labeled for both allergies and colds, may have an antihistamine in them to help with a runny nose and postnasal drip. Antihistamines are known to cause drowsiness in some people. If the medicine does not say it’s an antihistamine, look for these ingredients to know for sure: diphenhydramine, chlorpheniramine maleate and doxylamine succinate are all antihistamines.

Interactions with Other Medicines

If you have a known health condition or are taking other medications, check with your doctor before choosing a cold medicine from your local pharmacy or supermarket. You can also use one of the drug interaction checkers online, but it’s always safest to talk with your doctor who knows your health history.

To give you an idea of the problem combinations that exist, here are some examples: Decongestants and antihistamines may not mix well with drugs prescribed for heart disease or blood pressure problems. You will also want to check to make sure you’re not taking anything else with aspirin, acetaminophen or ibuprofen in it. If you have asthma, emphysema or other lung disease, you’ll want to check with your doctor before taking anything with a cough suppressant or expectorant in it. If you are on any anti-depressant or anti-anxiety drug, check with your doctor before trying any cough or cold medicine.

Combining certain meds can cause serious side effects, so this is even a good topic of discussion for you and your doctor before a cold or flu hits. Know which medications and ingredients are safe for you ahead of time and you’ll know exactly what to do if you get catch a cold or the flu.

BC® Powder Cold Medicines

BC® Cough & Cold targets cough and nasal congestion. It contains acetaminophen, dextromethorphan and phenylephrine, and should not make you feel sleepy.

BC® Sinus Pain & Congestion is for allergy, cold and sinus symptoms. It contains acetaminophen, phenylephrine and an antihistamine, chlorpheniramine maleate, so there’s a chance it could make you sleepy. Both cold medicines are in powder form and come in convenient stick packs you can slip in your pocket and take with you on the go, if needed.

The best cure for a cold is prevention, so we also recommend you read our blog post, “5 Easy Things You Can Do to Avoid Colds & Flu.”