How 8 Supplements Like Vitamin D and Omega-3 Interact with Medication

Harmful effects from supplements account for approximately 23,000 emergency room (ER) visits each year, while adverse medication reactions result in 1.3 million ER visits annually.

And if supplements and certain medications are taken together, they can also cause a negative reactions. The side effects range widely from increasing or decreasing the medicinal effect or causing a toxic reaction. While it's always important to consult a doctor before using medication, here are some examples of supplement and medication combinations that could cause health issues.

Omega-3 fatty acids, most commonly found in fish oil supplements, are used to mitigate heart disease, high blood pressure, and triglyceride reduction.

Researchers believe that omega-3 has an antithrombotic effect, so taking it with anticoagulant or antiplatelet drugs can lead to an increased risk of bleeding. Along with that, research also suggests that high levels of omega-3 may also decrease the effectiveness of hormone-based birth control.

Read More: Is It Bad to Take Pills On an Empty Stomach?

Taken for depression, ADHD, somatic symptom disorder, and menopausal symptoms, St. John’s wort can have some serious interactions with certain prescription medications. 

St. John’s wort can raise serotonin levels in the brain and, if combined with certain antidepressants, could lead to a toxic level of serotonin. It’s best to seek the advice of a medical professional if using St. John’s wort for depression. 

When taken with digoxin (used to treat heart failure and heart rhythm issues), St. John’s wort can lower the effectiveness of the drug. The supplement can even reduce the effectiveness of oral contraceptives, which could lead to pregnancy. 

Read More: Strange Side Effects From Supplements and What You Need to Know

Vitamin D is important for bone-building and maintenance. It also has antioxidant and anti-inflammatory properties.

Vitamin D can interfere with medications such as Lipitor (and possibly other statins) by increasing the body’s vitamin D levels. Too much vitamin D can lead to dehydration and nausea and may cause kidney stones. 

Blood pressure medications such as calcium channel blockers can become less effective when combined with vitamin D, while thiazide diuretics — also used to lower blood pressure —  increases renal calcium resorption and can result in hypercalcemia when taken with vitamin D.

Read More: Everything You Need to Know About Vitamin D

Vitamin E protects against damage from free radicals and clots and aids in immune function. 

Taking vitamin E interferes with the absorption of the following drugs: tricyclic antidepressants, antipsychotic medication, Thorazine, and beta blockers. Experts also believe that taking vitamin E with aspirin or blood thinners like Warfarin can increase the risk of bleeding. Research indicates that vitamin E can decrease the effectiveness of few chemotherapy drugs (e.g. cyclosporin).  

Read More: They May Taste Good but are Gummy Vitamins Effective?

This fat-soluble vitamin helps blood clotting and wound healing. There’s also increasing evidence that vitamin K supports bone health.

According to medical professionals, vitamin K reduces the blood-thinning effect of anticoagulants (such as Warfarin). When taken with cephalosporin antibiotics, the body’s ability to absorb vitamin K is reduced.  

Read More: Do Multivitamins Work and How Do You Know If You Need One?

Adequate calcium is needed for bone building and maintenance, as well as for muscle, heart, and nerve function.

While we need calcium for our bone and muscle health, taking calcium supplements with medications such as quinolone and tetracycline antibiotics can reduce the body’s ability to absorb those medications. 

Researchers also found that taking calcium supplements with the heart medication digoxin can cause a toxic reaction.

Read More: Is Milk Bad for You? Here's What the Science Says

Iron is a crucial component of hemoglobin and is also essential for making new blood cells and immune support.  

Iron decreases the absorption of the following medications: bile acids sequestrants, Levodopa (taken for Parkinson’s disease), quinolone and tetracycline antibiotics, the thyroid replacement drug, levothyroxine, and (blood pressure lowering) ACE inhibitors.

Taking iron supplements and acid-reducing medicine together can impact iron absorption, leading to iron deficiency. 

Read More: Everything You Need to Know About Iron Supplements

Vitamin B12 is needed for red blood cell formation and to support nerve cell function. It is also important for creating and regulating DNA. 

The following medications lower the absorption of vitamin B12: Metformin (used for diabetes), colchicine (used to prevent/treat gout), and aminosalicylic acid (used for tuberculosis). This can lead to the body producing red blood cells that are either too large or non functioning.   

Research also suggests that taking vitamin B12 with acid reducers can result in low absorption rates of vitamin B12. 

Read More: Your Guide to B12 Supplements: Everything You Need to Know About Them

Our writers at Discovermagazine.com use peer-reviewed studies and high-quality sources for our articles, and our editors review them for accuracy and trustworthiness. Review the sources used below for this article:

• National Institutes of Health. Omega-3 Fatty Acids. Fact Sheet for Professionals

• Journal of Trauma Nursing. Omega-3 Fatty Acid Supplementation and Warfarin: A Lethal Combination in Traumatic Brain Injury

• American Psychiatric Association. What is Somatic Symptom Disorder?

• National Center for Complementary and Integrative Health. St. John's Wort and Depression: In Depth

• Dermato-Endocrinology. Statins and vitamin D

• Pharmacognosy reviews. Free radicals, antioxidants, and functional foods: Impact on human health

• Nutrition research reviews. Vitamin E-drug interactions: molecular basis and clinical relevance

• Coimbra Health School. Calcium Interaction with Tetracyclines – What is Known?

• The Journal of Emergency Medicine. The Effects of Intravenous Calcium in Patients with Digoxin Toxicity

• Medline Plus. Taking iron supplements

• National Human Genome Research Institute. Deoxyribonucleic Acid (DNA) Fact Sheet

• National Institutes of Health. Vitamin B12