Naturopath promotes scientifically unsubstantiated claim that cayenne pepper is “the most powerful blood thinner”

Cayenne pepper is “the most powerful blood thinner”
Inadequate support: There is no scientific evidence supporting the claim that cayenne pepper is a powerful blood thinner.
Flawed reasoning: Blood thinners work by preventing blood clotting. On the contrary, the sealing of blood vessels to interrupt bleeding requires blood clotting. Thus, claiming that cayenne pepper can at the same time fluidify the blood and seal bleeding is contradictory.
Cayenne pepper is a plant commonly used to flavor dishes. Cayenne pepper contains capsaicin, a molecule responsible for the burning sensation when eating pepper. Capsaicin may increase the effect of blood thinners, a type of drug used to reduce the risk of blood clotting and thrombosis or embolism. However, cayenne pepper itself isn’t a potent blood thinner nor does it prevent bleeding, contrary to popular beliefs.

FULL CLAIM: Cayenne pepper is “the most powerful blood thinner” and is able to “seal any bleeds”


The saying “Food is medicine” encapsulates one of the guiding principles of healthcare, recognizing the role that our diet plays in our health. But this concept is sometimes oversimplified and exploited to spread attractive but unsubstantiated claims about the healing properties of various foods.

One example is the claim that cayenne pepper is “the most powerful blood thinner” and that it is able to “seal any bleeds” when it goes through the body. Blood thinners are substances that prevent blood coagulation or blood clotting. Thus some people may need to use blood thinner to lower their risk of blood clotting, which may cause thrombosis or embolism.

Naturopath Barbara O’Neill is among the sources of this claim, which she made in videos that are now being shared on TikTok and other platforms. O’Neill holds no relevant health-related qualifications and has a track record of spreading health misinformation. The New South Wales Health Care Complaints Commission barred her from providing any health services, after finding that she had told patients cancer could be cured with sodium bicarbonate (baking soda) and promoted misleading advice on pregnancy and child-rearing.

This is not the first time that unsupported claims attribute health benefits to cayenne pepper. For instance, cayenne pepper has been touted as a cure for stomach ulcer or a prevention against heart attack without scientific evidence.

Here as well, this is unsubstantiated. Cayenne pepper contains the molecule capsaicin, responsible for the burning sensation when ingested, and capsaicin may increase the effect of blood-thinning drugs. However, there is no supporting evidence that cayenne pepper is the most effective blood thinner. Cardiologist Geoffrey Barnes from the University of Michigan told Lead Stories:

“Cayenne pepper is not the most powerful blood thinner. There are multiple blood-thinning medications that have been tested on large groups of people and have been proven to thin blood. Cayenne pepper has not been tested in that way … There is no evidence that cayenne pepper … works as well as the drugs we have tested”

Furthermore, a search on the scientific literature repository PubMed for blood thinning properties of cayenne pepper returned no results#.

The claim also contradicts itself. As mentioned earlier, blood thinners prevent blood coagulation or blood clotting. However, blood clotting is necessary to stop bleeding by sealing off the ruptured blood vessels. Thus, a substance cannot at the same time act as a blood thinner and seal off bleeding, contrary to what the claim says. This is why people using blood thinners may experience side effects like spontaneous or prolonged bleeding. In his comment to Lead Stories, Barnes added “If it’s meant to seal blood, that goes against what a blood thinner is”.

In summary, the claim that cayenne pepper thins the blood but also promotes blood clotting at the same time is self-contradictory. There is no scientific evidence supporting the use of cayenne pepper as a blood thinner.



# Pubmed search query: (capsaicin[Title] OR cayenne[Title] OR annuum[Title] OR capsicum[Title]) AND (“blood thinner”[Title] OR “blood thinning”[Title] OR “blood-thinning”[Title] OR anticoagul*[Title])


Published on: 19 Oct 2023 | Editor:

Health Feedback is a non-partisan, non-profit organization dedicated to science education. Our reviews are crowdsourced directly from a community of scientists with relevant expertise. We strive to explain whether and why information is or is not consistent with the science and to help readers know which news to trust.
Please get in touch if you have any comment or think there is an important claim or article that would need to be reviewed.