4 Common Drug Interactions You Didn't Know About [OTC + Prescription]

Over the counter and prescription interactions

Many OTC (over the counter) medicines or supplements are fast, affordable remedies for many temporary ailments, but are not free from interacting with other drugs. This article will explore some surprising interactions that you probably didn’t know about.

Doctors and pharmacists work hard to ask all of the necessary questions with the goal to prevent potentially life threatening interactions, yet no human or process is perfect. Since these substances will ultimately enter your body, it is in your best interest to do your own double-check as well.

If you discover a potential interaction in this list or in your other research and you are taking both medicines, promptly contact a health professional for advice.

1. Saint John’s Wort + Birth Control Pills

Saint John’s Wort is a popular over the counter remedy for depression, and research indicates that it is on par with the conventional antidepressants know as SSRIs. It is one of the top selling herbal supplements in the United States.

Oral contraceptives are used by women to prevent pregnancy. The CDC estimates that about 28% of woman who are of childbearing age are on the pill.

What many don’t know is that taking Saint John’s Wort may reduce dose exposure of the medicine by up to 15% and decrease the effectiveness of common birth control pills.

If you are currently taking oral contraceptives to prevent pregnancy and taking St. John’s Wort, you might want to talk about other considerations with your doctor, or use a backup method as well.

Another OTC remedy that interferes with hormonal birth control is soy isoflavones

Other prescriptions medications that may interfere with birth control efficacy include prescription antidepressants and anti-anxiety medicines (such as benzodiazepines), some antibiotics, and anticonvulsant medicines for seizures.

2. Pain Relievers + Antidepressants

Sold under the brand names of Advil, Motrin and many generic names, ibuprofen is a popular pain reliever that belongs to a class of drugs known as non-steroidal anti-inflammatory drugs (NSAIDS). Aleve, generically known as naproxen is a popular brand of another OTC NSAID. These drugs are designed to reduce pain and inflammation, and are sold over the counter. NSAIDS are in many prescription medications as well.

There are many classes of antidepressants, but the ones we will mention for the purpose of this article are the serotonin reuptake inhibitors, or SSRIs. Popular SSRIs include Prozac (fluoxetine), Paxil (paroxetine) and Luvox (fluvoxamine).

According to this Harvard study taking an NSAID such as ibuprofen in combination with an SSRI makes the antidepressant less effective. Therefore, to get the most out of your SSRI it’s best not to take over the counter pain reliever at the same time. If you have chronic pain, consider discussing alternative approaches with your doctor.

On a side note, taking SSRIs in combination with NSAIDs (e.g. taking ibuprofen and fluoxetine) could also do damage to your stomach and intestines. (R)

3. Pain Relievers + Blood Pressure Medicine

While we’re on the subject of NSAIDS you might not want to take these along with your blood pressure pills either. According to WebMD NSAIDs can actually raise blood pressure and make your blood pressure medicine less effective.

4. Benadryl + Benadryl

No, that’s not a typo! We used the popular brand name of the drug in the header since most people know diphenhydramine as Benadryl.

Diphenhydramine, taken orally, is a common antihistamine and over the counter sleep aid. It appears as an ingredient in many brand name and generic products for these purposes.

Diphenhydramine is also used topically to control itching from bug bites, sunburn, poison ivy, and other minor skin irritations. Topical products include Benadryl® Itch Stopping Cream and Dermagesic® Liquid and many generics for these purposes.

Don’t use diphenhydramine both topically and orally at the same time.

Since topical diphenhydramine could enter the bloodstream, the combination of the two may cause diphenhydramine toxicity. That is, it could create the same symptoms you would experience by overdosing on diphenhydramine.

Although this warning is marked on the product packages, most people overlook it.

Little Change IconMake this Little Change

In addition to receiving your doctor’s and/or pharmacist’s advice, spend some time investigating some drug interactions on your own using sites such as drugs.com and report any concerns you find to your doctor or qualified medical professional.

About 128,000 people die each year from taking drugs that are prescribed to them. Many complications are due to interactions between drugs that got overlooked in the process. Making the suggested Little Change above could make you aware of potentially risky combinations.

This article is not a list of the most common or most deadly drug interactions, rather some of the most overlooked or most surprising. Do not make any changes to any medicines you are taking without the advice of a qualified medical professional.

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