Supplements and Medications: What to Know Before Taking Them Together

If you're 40 or older and take prescription medications, over-the-counter drugs, or dietary supplements, it's worth keeping a list of everything you take to share with your doctor or pharmacist.

Certain supplements can change how a medication works. They may make a medicine less effective or even increase the risk of certain side effects.

Before adding a new supplement to your routine, check the label and ask your doctor or pharmacist whether it could affect anything you're already taking.

In this article, we'll cover some common supplement and medication combinations to ask about, how to check for potential interactions, and a simple checklist you can bring to your next doctor's appointment.

Do Supplements Really Interact With Medications?

Yes, some do. According to the FDA, certain supplements can affect how your body absorbs, breaks down, or clears a medication. This can cause either too much or too little of the medication to stay in your system.

The potential for an interaction also increases when you’re taking several medications and supplements together. That doesn't mean you need to be concerned about every combination. Tens of millions of people in the U.S. take dietary supplements along with prescription medications each day. The CDC found that 38.7% of U.S. adults used two or more dietary supplements during 2021-2023. That number increased from 23.4% among adults ages 20-39 to 38.5% among adults ages 40-59 and 56.4% among adults 60 and older.

Remember that just because a supplement is labeled "natural" doesn't mean it won't interact with a medication. Before adding a new supplement to your routine, check the label and ask your doctor or pharmacist whether it could affect anything you're already taking.

Which Supplements Should You Check With Common Medications?

Some supplement and medication combinations come up more often than others. The right answer depends on the medication you're taking, the dose, your health history, and any other supplements in your routine.

Before adding a new supplement, we recommend talking with your doctor about potential interactions. It also helps to know how to read a supplement label, so you know exactly which ingredients and amounts you're taking.

Here are a few common combinations to ask about:

If you take	Ask about	What to ask your doctor or pharmacist
Blood thinners like warfarin	Vitamin E, vitamin K, turmeric, or other supplements	Could this affect my bleeding risk or how my medication works?
Thyroid medicine such as levothyroxine	Iron or calcium supplements	How far apart should I take these?
Some antibiotics	Magnesium, calcium, iron, or other mineral supplements	How many hours apart should I take these?
Blood pressure or heart medication	Caffeine-containing supplements	How much caffeine is appropriate for me?
Prescription or over-the-counter sleep medication	Sleep supplements such as DreamZzz	Could these products increase drowsiness when taken together?

Be sure to remember that these are common examples, not a complete list.

Blood Thinners

If you take a blood thinner like warfarin, ask about every supplement you take. The FDA lists vitamin E and ginkgo among supplements that can affect bleeding risk. It also warns that combining warfarin with supplements or other products that affect blood clotting can increase the risk of bleeding. The AARP also recommends discussing turmeric supplements with your doctor or pharmacist.

Vitamin K is another consideration with warfarin. The National Institute of Health (NIH) Office of Dietary Supplements recommends keeping your vitamin K intake consistent from day to day if you take warfarin, including vitamin K from food and supplements.

That matters if you regularly use a greens powder such as Field of Greens, which contains some vitamin K. This doesn’t necessarily mean you need to avoid it, but your doctor should know you're taking it so they can factor it into your overall vitamin K intake.

Thyroid Medicine, Calcium, and Iron

Certain minerals can reduce how much of a medication your body can absorb when you take them together.

Iron is one example. The NIH notes that iron can reduce the absorption of levothyroxine, a common thyroid medication. If you're taking a multivitamin like Fortify, check the label for iron and ask your doctor or pharmacist about the dosage and how far apart you should take the two products.

Calcium can also interfere with the absorption of certain medications. Your doctor or pharmacist can tell you whether you need to separate your medication from a calcium-containing supplement and how much time to leave between them.

Antibiotics and Mineral Supplements

Magnesium and other minerals can interfere with the absorption of some antibiotics. If you’re taking an antibiotic and a magnesium supplement, the NIH recommends asking your healthcare provider whether you should take them at different times.

This is another reason to look at the full ingredient list rather than focusing only on a supplement's primary ingredient. A product can contain several vitamins and minerals that you might not think to check for individually.

Blood Pressure Medicine and Caffeine

Caffeine can come from more than just your morning coffee. Supplements such as pre-workout powders, energy formulas, and some weight-management products can also contribute to your total daily caffeine intake.

If you take blood pressure or heart medication, show your doctor or pharmacist the supplement label and ask whether the caffeine fits with your medication and your overall daily intake.

Some BrickHouse products like Lean and Dawn to Dusk contain caffeine, so check the label for the amount you're getting from supplements in addition to coffee, tea, energy drinks, and other sources.

Sleep Supplements and Prescription Medications

Sleep supplements are worth checking if you're already taking medications or other products that affect alertness or sleep. Combining products with similar effects can increase drowsiness and other side effects.

If you take a prescription sleep medication or another product that causes drowsiness, ask your pharmacist before adding DreamZzz or another sleep supplement to your routine.

These are just a few common examples. If you take several medications or supplements, bring your complete list, or the actual bottles and tubs, to your next doctor or pharmacy visit.

How Do You Check for Supplement and Drug Interactions?

Online interaction checkers can be a useful first step when you want to see whether a medication and supplement have a known interaction.

There are free tools available from WebMD, Medscape, and Drugs.com that allow you to search medications and, depending on the tool, supplements, herbs, foods, and other products. These databases are useful reference tools, but they shouldn't replace advice from your doctor or pharmacist.

One limitation is that an interaction checker may not have every supplement ingredient or product formulation in its database. This matters when you're taking a supplement like a greens powder, multivitamin, or another product with several ingredients.

For example, caffeine is easy to search for on its own. However, a less common ingredient, such as the caffeine-containing co-crystal in Dawn to Dusk, may be harder to find in a general interaction database. If you can't find an ingredient or aren't sure how to interpret the result, that's a good reason to ask your doctor or pharmacist.

If an online checker flags a possible interaction, don't stop taking your medication on your own. Write down the medication and supplement involved and ask your doctor or pharmacist what the result means for you.

Your doctor or pharmacist can look at the full picture, including the medication and supplement doses, when you take them, your other medications, and any health conditions that could affect the combination.

Using the same pharmacy for your prescriptions can also make it easier for your pharmacist to see your complete medication list and check for potential interactions.

A Simple Checklist to Bring to Your Pharmacist

The FDA recommends keeping a list of everything you take, including the dose and how often you take it.

You can make your own list in about 10 minutes, or download our printable checklist here and bring it with you to your pharmacist or next doctor's visit.

Write Down Everything You Take

Start with your prescription medications. Then add over-the-counter pain relievers, allergy medicines, vitamins, minerals, powders, gummies, and other supplements.

If you scoop it, stir it, chew it, or swallow it, put it on the list.

Add the Dose and Time of Day

You don't need a complicated spreadsheet.

"Morning with breakfast" or "evening before bed" is enough.

The timing can matter when you're taking medications and supplements together, so give your pharmacist a clear picture of your daily routine.

Bring the Bottles and Tubs

When possible, bring the actual products with you. The label shows the exact ingredients and amounts. That's information a handwritten list can easily miss.

Use One Pharmacy

Using one pharmacy gives your pharmacist a more complete picture of what you're taking.

If you use mail-order prescriptions or fill some medications at another pharmacy, be sure to add those medications to your list.

Ask If Anything Needs to Be Spaced Apart

Some medications and supplements shouldn't be taken at the same time.

Ask your doctor or pharmacist whether you need to separate any of your morning, afternoon, or evening products.

This is especially useful if you take several products at night, such as DreamZzz, prescription medications, or other products that can cause drowsiness.

Update Your List When Something Changes

A new prescription is a good reason to review your entire list. So is a change in dose or a new supplement.

Keep your list somewhere easy to find, such as inside a kitchen cabinet or on your phone, so it's easy to update.

Frequently Asked Questions

Do supplements interact with medications?

Some do. According to the FDA, certain supplements can change how your body absorbs, breaks down, or clears a medication. That can make the medication stronger or weaker than intended. Keeping an up-to-date list and reviewing it with your pharmacist is a good way to catch potential problems.

Are supplements considered medications?

No. The FDA regulates dietary supplements differently from prescription and over-the-counter drugs. We still recommend putting your supplements on the same list as your prescriptions so your doctor and pharmacist know everything you're taking.

Some supplements may also qualify for HSA or FSA spending, depending on the product and your plan.

How can I check if a supplement interacts with my medication?

You can start with an online drug interaction checker, but don't rely on one alone. Your doctor or pharmacist can review the full list of medications and supplements you take and help determine whether an interaction is relevant to you.

Keep Your Supplement List Up to Date

You don't need to memorize every possible supplement and medication interaction.

Keep one current list. Bring it to your doctor and pharmacist. Check it whenever you start, stop, or change a medication or supplement. And if you're considering a new supplement, bring the bottle or label with you and ask before adding it to your routine.

If you're still deciding which products fit your routine, you can take the BrickHouse Product Quiz and bring the results to your next doctor visit.

Sources

1. U.S. Food & Drug Administration (FDA): Mixing Medications and Dietary Supplements Can Endanger Your Health
2. CDC: Dietary Supplement Use: United States, August 2021–August 2023
3. AARP: Cautions When Taking Multiple Medications
4. AARP: Supplement Safety Tips for Older Adults
5. AARP: Mixing Prescription Drugs and Supplements
6. NIH Office of Dietary Supplements: Iron Fact Sheet for Health Professionals
7. NIH Office of Dietary Supplements: Magnesium Fact Sheet for Consumers
8. NIH Office of Dietary Supplements: Vitamin K Fact Sheet for Consumers
9. National Center for Complementary and Integrative Health (NCCIH): How Medications and Supplements Can Interact
10. MedlinePlus: Did You Know Supplements and Medications Can Interact in Unexpected Ways?