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Safely Using OTC Medicines (For Colds & Flu & Allergies) While Taking Prescription Drugs

Posted November 12, 2010 featuring Val Jones, M.D.

Val Jones, M.D.

C.E.O., Better Health

Photo of Val Jones, M.D.

Val is an award-winning author and blogger, regular guest on ABC News in Washington, DC, CEO of Better Health, and sees patients part-time at DocTalker Family Medicine in Vienna, Virginia.


Each year, an estimated 5 to 20 percent of Americans come down with the flu. We catch over 1 billion cold virus infections per year, and 1 in 5 of us suffers from allergy symptoms on a regular basis.

Because so many consumers rely on over-the-counter (OTC) medicines to treat a wide array of symptoms, and almost half of all Americans take at least one prescription drug, it is important that consumers are aware of any possible OTC medicine interactions with prescription medications. Drug interactions can result in unwanted effects and prevent a medicine from working, so it is important that you know what tools you can use to avoid any possible interactions. I hope that this article will serve as a reminder to check both the Drug Facts label on your OTC medicines and/or with your doctor if you have any doubts about whether or not it’s safe for you to use the OTC product(s).

Cold And Flu Medicines

Cold and flu medicines have active ingredients designed to treat four basic categories of symptoms (pain/fever; coughing; thick mucus; congested nose). Highlighted below are some common prescription drug interactions that can occur with these different classes of ingredients so that you can see at a glance if you might be at risk. (Please note that this is not an exhaustive list, but a starting point to remind you to check your Drug Facts labels and/or speak to your doctor). If you’re unsure about the difference between a cold and the flu, learn more at familydoctor.org.

*Table information derived from Drug Facts labels. Medicines are taken by mouth unless otherwise indicated.

As you can see, some OTC cold and flu medicines can interact with a number of prescription drugs. This is why it’s so important to review carefully the warnings listed on your Drug Facts labels, and to discuss your medication regimen and condition list with your doctor if you think that there may be a possibility for an unwanted interaction. Remember that many cold and flu medicines contain multiple active ingredients.  Be careful not to exceed the recommended dose of any ingredient by checking the Drug Facts labels. (For example, two different OTC medicines might both contain acetaminophen).

Keep in mind that there are some non-medicinal treatment options for cold and flu symptoms. These may help with additional symptom relief, or they could provide you with more treatment options if OTC drugs are not appropriate for you.

Test Your Knowledge

Q: What is benzonatate and how does it work?

A: Benzonatate (also known as Tessalon Perles) is a cough suppressant chemically related to local anesthetics. It acts by making the throat tissues less sensitive. Benzonatate was first approved for use by the FDA in 1958.

Seasonal Allergy Medicines

OTC medications that treat seasonal allergy symptoms are typically antihistamines or decongestants. Antihistamines help to relieve itching and sneezing, while decongestants may improve breathing by clearing the nasal passages. “First generation antihistamines” were first discovered/created in the 1940s and are more likely to cause drowsiness than the newer, “second generation anti-histamines.”  Many allergy medicines offer a combination of both antihistamines and decongestants, so it’s important to look at the active ingredient list to make sure that they’re appropriate and safe for you to use.

In the following table, you can review some of the most common OTC antihistamines and decongestants, along with their potential interactions with prescription drugs. As you can see, medicines that are taken by mouth are more likely to react with other prescription drugs than are OTC medicines contained in nasal sprays and eye drops.

*Table information derived from Drug Facts labels. Medicines are taken by mouth unless otherwise indicated.

In addition to OTC medicines with active ingredients, salt-water (“saline”) solution is available as a nasal spray to relieve mild congestion, loosen mucus, and reduce crusting. Artificial tears are available to treat itchy, watery, and red eyes.

Allergy sufferers may benefit from reviewing the Mayo Clinic’s excellent list of tips for allergy-proofing the home. These tips include everything from bedding changes to air filtration systems. There are many good options for allergy treatment and prevention and I hope that you will find the best solution to help you breathe easily – without any unwanted interactions with your prescription medicines.

Test Your Knowledge

Q: What’s the most common side effect of first-generation anti-histamines? Why?

A: Drowsiness. Because the medicine works to reduce histamine release throughout the body, but also triggers drowsiness by activating certain brain receptors. 

About From the Experts

OTCsafety.org has partnered with Better Health, MedHelp, and third-party experts to create the From the Experts resource, a section dedicated to providing you with information from experts about the safe use of OTC medicines for you or your loved ones.

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