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What Do Over the Counter Cold Remedies Do?

Medically reviewed by Carmen Pope, BPharm. Last updated on May 10, 2023.

Official answer


Decongestants Unblock Your Nose

A cold wouldn't be a cold without congestion. Viruses that cause colds stimulate the release of mucus from your nasal passages which builds up, adding a kind of muffled, nasal quality to your voice.

Decongestants turn off this mucus release and unblock the nose, allowing you to once again smell that coffee and sound human again. Phenylephrine and pseudoephedrine are the most commonly used oral decongestants, while oxymetazoline can be found in nasal drops or sprays. FDA regulations state that pseudoephedrine must be kept behind the pharmacy counter and there are limits as to how much you can buy each day and month.

Do not use decongestant nasal sprays for more than 3 days at a time because they can cause rebound congestion.

Antihistamines Dry Up a Runny Nose

You could probably cope with just congestion; but no, your nose decides to drip like a tap as well.

Antihistamines dry up drips and can be grouped into two main types: sedating and non-sedating. If you are planning to work, drive, or operate any kind of machinery, always select a non-sedating antihistamine such as loratadine (Claritin, Alavert) or fexofenadine (Allegra). The product cetirizine (Zyrtec) has a higher chance of causing drowsiness, although most people never experience it.

Take sedating antihistamines like brompheniramine, chlorpheniramine, or diphenhydramine (Benadryl) at bedtime, if possible, to help prevent daytime grogginess. Avoid alcohol while you are taking a sedating antihistamine.

Cough Suppressants Stop a Dry, Tickly, 'Ahem'-Type of Cough

Dry, tickly coughs are actually more common with the flu than a cold. You will know that your cough is dry if you want to clear your throat all the time, making the 'a-hem' sound.

Many commonly used OTC cough suppressants contain dextromethorphan (Silphem DM, Dayquil Cough). Codeine also has cough suppressant actions but is only available in some states. It may be combined with an expectorant called guaifenesin. Codeine-containing cough syrups can be accessed without a prescription from your pharmacist with special restrictions: brands include Cheritussin AC.

Expectorants Make It Easier to Cough Up Sticky Phlegm

Chesty coughs are more common with colds. If you have a cough with mucus, the last thing you want to do is stop yourself from coughing, so cough suppressants are not for you.

Instead, use an expectorant such as guaifenesin (Mucinex) to rid your lungs of all that sticky gunk that is floating around in there. Expectorants thin mucus making it much easier to cough it up and out. If you have green-colored mucus, chest pain when coughing, or fever, make an appointment to see your doctor.

Related Questions

Sinus Pain or Headaches From Colds

Most people get a bit of a headache with a cold, often due to sinus pain from clogged nasal passages.

Pain medicines such as acetaminophen (Tylenol), aspirin, and ibuprofen (Advil, Motrin) work well when combined with decongestants and will quickly relieve sinus pain or a headache.

Be careful not to double up on doses of pain relievers like acetaminophen or ibuprofen that are commonly present in combination cold and flu products.

Blocked Nose Only? Target With Nose Drops or a Spray

Maybe you have a minor cold or do you just want to clear your nasal passages before flying? Products are available that contain decongestants such as oxymetazoline (Afrin, Neo-Synephrine) to relieve congestion, but remember not to use for more than three days at a time to avoid rebound congestion.

Drug-free products that contain saline, such as Ayr Saline, are a good option for children and pregnant women. Saline improves mucus flow and can be used long-term.

Eye Drops Relieve Red, Tired Eyes

Many people find that once they sort out their nasal congestion, any eye symptoms resolve as well. So most people do not require eye drops for a cold.

However, if your eyes are still suffering, then eye drops are available that contain antihistamines and/or decongestants. But make sure you only use them for a couple of days at a time. If your eye symptoms persist for longer than this, it may be due to more than just a cold, so see your eye doctor for a check-up.

Final Words Of Advice

So before you buy any medicine over-the-counter, check out the ingredient list on the label. Remember to:

  • Choose products that ONLY contain the ingredients you need (no cough? You don't need a cough suppressant like dextromethorphan)
  • Watch for double-ups - especially with pain relievers (if your cold remedy contains acetaminophen, don't take extra Tylenol)
  • Check with your pharmacist to be sure your OTCs won't interact with any of your regular meds
  • Always see your doctor if you don't get any better, or get worse!

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