A Guide to Supplement-Medication Interactions


While many natural remedies are relatively harmless, they can have strong negative effects when combined with certain medications or medical conditions. It’s important to be aware of these interactions and to avoid anything that could be harmful or counterintuitive.

Generally, any substance that increases or decreases the mechanism that a certain medication is providing can be harmful. For example, when taking blood thinning medications, it is not safe to also take licorice root, as it is a natural blood thinner and may thin the blood too much. Conversely, taking too much vitamin K will promote blood clotting, and may reduce the blood thinning effects of the medication - also something to avoid.

Below is a list of common medications, alongside the herbs and supplements which should be avoided or limited when taking them due to potential adverse interactions. These are general guidelines only. Always check with your health care practitioner before adding any herbs or supplements to your daily routine if you’re already taking medication(s).

If you’re on blood pressure medications (blood thinners)…


Herbs and supplements that naturally thin the blood, as the blood could become too thin:


Vitamin E


Ginger (in high doses)

Turmeric (in high doses)

As well as blood-coagulating substances:

Vitamin K

If you’re on antidepressant medications such as selective serotonin reuptake inhibitors (SSRIs)…



St. John’s Wort



European buckthorn

Also avoid anything with a strong laxative or detoxifying effect, such as:

Alder buckthorn

Aloe (internal use)



Excessive vitamin C

Excessive magnesium

Slippery elm

Activated charcoal

Grapefruit seed extract

If you’re on insulin…

Insulin is used to regulate blood sugar in the body in diabetic patients by stimulating cellular uptake of glucose.


Chromium – as it is also effective in balancing blood sugar and lowering blood sugar levels. If taken with insulin, it’s possible that blood sugar levels could drop too low.

If you have goiter…


Foods that are “goitrogenic” (aka goiter-promoting), such as:


Brussel sprouts




Bok choy



Detoxification caution

If you take any medication(s), it’s best to avoid regular use of liver-cleansing herbs and supplements (Milk thistle, dandelion, burdock, berberine, nac, glutathione) as well as regular use of diuretics and laxatives which may clear the body of the medication before it has fully done its job.  

Whole foods diet

The best way to support your body on any medication is to consume a healthy, whole foods diet with plenty of fresh vegetables, fruits, whole grains, nuts, seeds, and lean protein.

If you’re thinking of taking a new supplement or herb and you’re on medication(s), it’s always best to do a bit of research to check for interactions. If you’re still unsure if a herb or supplement is right for you, speak to a holistic practitioner.