Use caution when combining prescriptions with cold medicine

Cold and flu season is upon us.

Cold and flu season is upon us. While you are busy stocking up on cold medicines, be aware of a lurking danger — combining certain prescription medications with cold medication.

Kristin M. Tobe, M.D., family medicine physician, is very cautious when recommending cold medicine to her patients.

“In general, I advise most patients taking prescription medications to avoid cold medicine — and really any over-the-counter products — without checking with me first,” Dr. Tobe said.

According to Dr. Tobe, definite “don’ts” when it comes to over-the-counter medications are herbal remedies and medicines containing pseudoephedrine, such as Sudafed.

One danger from mixing cold medicines with prescriptions is the potential for new or increased side effects that can be harmful to your health. Cold medicines can trigger side effects such as elevated blood pressure, dry mouth, dizziness, drowsiness or heart palpitations. These can worsen when the medicine is taken along with a prescription medication that has its own side effects.

One of the most serious dangers of combining medicines is an adverse effect on the levels of medication in the bloodstream.

“Cold medication ingredients can compete for metabolism by the liver, resulting in higher or lower blood levels of the prescription drug,” Dr. Tobe said. If you feel you must take cold medicine, Dr. Tobe says less is more.

“You should choose your most bothersome symptom and treat that with a single-ingredient over-the-counter medication,” she said. “In the end, there is no substitute for rest and fluids!”

If you are taking prescription medicine and worry about potential negative reactions with other medicines, your physician or pharmacist can help. “Patients considering buying over-the-counter products should speak with their pharmacist or doctor first,” Dr. Tobe said. “We have access to large databases that can quickly check for interactions.”

Hidden Rx dangers

Avoid cold medicine if you take any of these types of prescription medications:

  • Antihypertensives (for high blood pressure)
  • Antiarrhythmics (for irregular heartbeat)
  • Anticoagulants (blood thinners)
  • Antidepressants
  • Pain medications containing acetaminophen
  • Glaucoma medication

About our expert
Kristin M. Tobe, M.D., practices at Norton Community Medical Associates – Fern Creek, 9342 Cedar Center Way, Louisville, KY 40291; (502) 239-3228


(502) 629-1234

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