Did you know? Supplements and medications can interact in unexpected ways

Many of us take dietary supplements such as vitamins, minerals, herbs, or other products to boost our health. Since many supplements contain natural ingredients, it’s easy to assume they are always safe. But just because something is “natural” doesn’t mean it’s without risk—especially when combined with medications.

Do you take prescription or over-the-counter medications? If so, it’s important to know that supplements might change how those medications work.

How supplements can affect your medications

Some supplements can affect the way your body processes medications. This can lead to unexpected or even dangerous results.

Certain supplements can cause medications to break down faster than normal. This reduces the amount of medicine in your bloodstream and makes it less effective. Others may slow down this process, causing medications to stay in your body for too long. This can increase the risk of side effects.

For example, herbal St. John’s wort supplements, which are often used for mood disorders, can speed up certain processes in your body. This may prevent medications such as birth control pills, antidepressants, blood thinners, and some cancer treatments from working correctly.

Similarly, concentrated green tea extract can interfere with medications for heart conditions and other chronic diseases. This can pose serious risks when treating these conditions.

Before you buy, get the facts!

Want to make informed choices about herbal supplements and other natural products? NCCIH’s Herbs at a Glance series provides clear, science-based information about popular herbs and botanicals. Understanding the research can help you make better decisions about your health.

Protect your health and keep your treatments working as intended

To avoid potentially harmful interactions, always keep your health care providers in the loop about any and all medications, supplements, or herbal remedies you’re using.

Understanding the science

You know the basics, now Know the Science: How Medications and Supplements Can Interact! This handy digital resource from the National Center for Complementary and Integrative Health (NCCIH) provides information about interactions between supplements and medication to help you understand the risks. It also offers practical advice such as:

• Why it’s important to speak with your doctor and other health care providers about what you’re taking (and what information you should share with them)
• How different supplements might impact your medication’s effectiveness
• Common interactions to watch out for, including how supplements could interact with surgical procedures
• Tips for how to read labels on dietary supplements

Test your knowledge

Think you have a handle on medication–supplement interactions? Take a short quiz to see how well you understand the risks! It’s a fun way to ensure you’re making informed decisions about your health.

*This article was originally published in December 2021. It has been updated.