3 Surprising Things that Can Affect Your Medication
When taking prescription medications, most people focus on dosage and timing—but everyday foods, drinks, and supplements can quietly interfere with how your medication works. Some interactions can reduce a medication’s effectiveness, while others can lead to potentially harmful side effects.
Knowing what to avoid can help you get the most benefit from your medications and stay safer. Here are three surprising things that can alter how your prescriptions work.
1. Grapefruit and Medication Interactions
Grapefruit juice is well-known for interacting with dozens of prescription medications. According to Harvard Health (2021), researchers believe that a compound called furanocoumarin may be responsible for these interactions. Furanocoumarins are found not only in grapefruits but also in sour oranges and tangelos.
Here’s how it works: grapefruit juice blocks an important enzyme (CYP3A4) in the small intestine that helps metabolize certain drugs. When this enzyme is inhibited, medication absorption can increase significantly, leading to dangerously high levels of the drug in your bloodstream.
Medications Commonly Affected by Grapefruit Juice:
Blood pressure medications
Cholesterol-lowering statins
Anti-anxiety and antidepressant medications
Tip: Always check with your pharmacist or healthcare provider to see if you should avoid grapefruit or grapefruit juice with your prescription.
2. Alcohol and Prescription Medications
Alcohol is another substance that can interfere with medications in several ways. Drinking alcohol while on certain medications can:
Decrease the effectiveness of the medication
Worsen medication side effects
Create toxic interactions in the body
Heighten the sedative effects of alcohol, increasing risk of accidents or overdose
According to GoodRx (n.d.), alcohol interacts most dangerously with medications such as:
Pain relievers, including opioids
Anti-anxiety medications like benzodiazepines
Blood thinners like warfarin
Sleep aids and sedatives
In addition, mixing alcohol with over-the-counter pain relievers such as ibuprofen or acetaminophen can put unnecessary strain on the liver and increase the risk of liver damage.
Tip: Always consult your pharmacist or physician about whether it’s safe to consume alcohol while taking your medications.
3. St. John's Wort and Its Effects on Medications
St. John's Wort is a widely used herbal supplement often marketed for improving mood and supporting emotional well-being. However, according to the Therapeutic Goods Administration (TGA, 2022), it can significantly reduce the effectiveness of many prescription drugs.
St. John’s Wort works by inducing certain liver enzymes (especially CYP3A4), which speeds up the breakdown of medications. As a result, the drug leaves the bloodstream faster than intended, reducing its therapeutic effect.
Medications Commonly Affected by St. John’s Wort:
Anticoagulants (blood thinners)
Anticonvulsants (seizure medications)
Oral contraceptives (birth control pills)
Some antidepressants
Tip: If you are considering taking St. John’s Wort, speak with your healthcare provider first to avoid unintended interactions.
References
Good Rx. (n.d.). Side effects - goodrx. Good Rx. Retrieved December 28, 2022, from https://www.goodrx.com/drugs/side-effects
Harvard Health. (2021, March 30). Grapefruit and medication: A cautionary note. Harvard Health. Retrieved December 28, 2022, from https://www.health.harvard.edu/staying-healthy/grapefruit-and-medication-a-cautionary-note
Therapeutic Goods Administration (TGA). (2022, June 21). St John's wort: Important interactions between st john's wort (Hypericum perforatum) preparations and prescription medicines. Therapeutic Goods Administration . Retrieved December 28, 2022, from https://www.tga.gov.au/news/safety-alerts/st-johns-wort-important-interactions-between-st-johns-wort-hypericum-perforatum-preparations-and-prescription-medicines
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