Supplements: Side Effects and Drug Interactions
Many people across Canada and throughout the world take supplements daily because of an inadequate intake of certain nutrients from their diets alone or to prevent or alleviate various deficiencies or ailments they may have. What people don’t realize is that supplements themselves may cause side effects and interactions with drugs they are taking. Even medications they take may decrease or increase the levels of certain vitamins and minerals in their body, requiring supplements to correct the deficiencies.
It is therefore important to be aware of the important side effects and interactions of the most common supplements used, as well as nutrient deficiencies that may occur as result of taking certain medications.
Calcium intake is essential to bone health through all stages of life and proper functioning of the heart. It is also the recommended treatment along with certain medications in diseases such as osteoporosis. There are a few notable drug interactions that may occur when they are taken with calcium:
- The absorption of bisphosphonates (ex. alendronate), medications for osteoporosis, may be decreased if taken together with calcium. This may decrease the effectiveness of the medication. It is therefore recommended to take alendronate at least 30 minutes before calcium.
- Calcium might decrease the absorption of iron. It is important to separate the intake of both by 2-4 hours to avoid an interaction.
- A certain group of antibiotics known as tetracyclines bind easily to calcium and may have decreased absorption and effectiveness when taken with calcium. Avoid taking calcium 3-4 hours before or after taking a tetracycline.
- To help increase the absorption of calcium, vitamin D should be taken with calcium.
One of the major building blocks of red blood cells is iron. Without a proper amount of iron, there will be a low amount of healthy red blood cells, causing a condition known as anemia. Iron supplementation will be recommended by your health care professional. Iron may cause several side effects and drug interactions:
- The most typical side effects are gastrointestinal in nature such as constipation, darkening of stools, nausea, vomiting, and stomach cramps. Taking it with food may prevent or lessen those effects.
- Iron may reduce the absorption of medications such as bisphosphonates, levothyroxine (used to treat low thyroid hormone levels), quinolone antibiotics (ex. ciprofloxacin), and tetracyclines. These drugs should be administered 2 hours before or after taking iron.
- Taking antacids containing aluminum, magnesium, or calcium may hinder the absorption of iron.
Cobalamin, also known as vitamin B12, is an essential vitamin for mental function, proper red blood cell function, and vital in pregnancy, among other important contributions. It has been recently discovered that long term use of metformin (a type 2 diabetes medication) can contribute low absorption of dietary vitamin B12 and therefore decrease blood levels of the vitamin. Your health care professional will monitor your blood levels if you are taking metformin and recommend vitamin B12 if needed.
Talk to your Health Care Professional
The supplements mentioned above are among thousands currently on the market that may interact with your current medications and cause side effects that can range from minor to major. It is important to tell your doctor and pharmacist about all the supplements you take, including a daily multivitamin. Your pharmacist is a great resource to help you avoid drug interactions and minimize side effects relating to your supplement intake.
- Calcium Salts, Oral. Compendium of Pharmaceuticals and Specialties. Canadian Pharmacists Association (2016)
- Vitamin B12. Compendium of Pharmaceuticals and Specialties. Canadian Pharmacists Association (2016)
- Vitamin B12. In D.S. Basow (Ed.), UpToDate. Retrieved from uptodate.com
- Iron Preparations. Compendium of Pharmaceuticals and Specialties. Canadian Pharmacists Association (2016)
- Compendium of Pharmaceuticals and Specialties. Canadian Pharmacists Association (2016)
- Schrier, S.L (2017). Causes and diagnosis of iron deficiency and iron deficiency anemia in adults. In D.S. Basow (Ed.), UpToDate. Retrieved from uptodate.com
- Common Anemias. Compendium of Therapeutics Choices. Canadian Pharmacists Association (2016)
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This article was provided by the clinical pharmacy at Rx Infinity. Rx Infinity provides optimal and sustainable patient management solutions through customized programs, innovative technology and added value services that improve the overall patient experience; while helping payers and plan sponsors achieve sustainability in the management of drug plans expenditures.
This information is not intended to be a substitute for professional medical advice, diagnosis or treatment. Always seek the advice of your physician or other qualified health provider with any questions about your medical condition. Do not disregard professional medical advice or delay seeking advice or treatment because of something you have read here.