The short answer
Aristolochic acid is a natural chemical in some plants used in herbal remedies. It causes urinary-tract cancers and kidney damage. Avoiding products that contain Aristolochia plants is the key step.
Aristolochic acid is classified as a known human carcinogen (IARC Group 1).
People are mainly exposed by taking herbal products that contain Aristolochia plants.
It is most strongly linked to cancers of the upper urinary tract.
A carcinogen classification describes hazard — whether something can cause cancer — not your personal risk at a given exposure.
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This page is for anyone who uses herbal remedies and wants to know about aristolochic acid. It explains what it is, how people are exposed, and its link to cancer.
The simple version
Aristolochic acid is a natural substance. It is found in a group of plants — Aristolochia and related species — used in some traditional herbal remedies. Taking products that contain it can damage the kidneys and cause cancers of the urinary tract.
What it is
Aristolochic acids occur naturally in Aristolochia plants (birthwort, pipevine) and Asarum plants (wild ginger). These plants grow worldwide. Herbal products that contain them are marketed as dietary supplements or traditional medicines, for conditions such as arthritis, gout, and inflammation. The FDA has not approved these products.
How people are exposed
Common ways people come into contact with it:
- Taking herbal remedies or supplements that contain Aristolochia plants.
- Eating or drinking a herbal or food product that contains them without knowing it.
The cancer connection
NCI reports cancers of the upper urinary tract in people who had kidney damage caused by herbal products containing aristolochic acids. The upper urinary tract means the renal pelvis and the ureter. Bladder cancer has been reported too.
The International Agency for Research on Cancer (IARC) is the World Health Organization's cancer-research agency. It places aristolochic acid in Group 1, carcinogenic to humans. That is the strongest evidence category. It means there is enough evidence that the substance can cause cancer in people. The US National Toxicology Program also lists aristolochic acids in its Report on Carcinogens.
Hazard is not the same as risk
Two ideas are easy to mix up: hazard and risk. An agency that lists aristolochic acid as a carcinogen is talking about hazard. That means the substance can cause cancer under some conditions. It is not a statement about your own risk. Your risk depends on how much you are exposed to, for how long, and other factors. Two substances in the same group can carry very different real-world risks. The label answers "can it cause cancer?" It does not answer "how likely is it to cause cancer for me?"
How to lower your exposure
- Avoid herbal products that list Aristolochia, birthwort, or related plants.
- Check the FDA's list of products known to contain aristolochic acids.
- Tell your doctor about every herbal product you take.
Are you looking at your overall cancer risk? Small, steady steps add up. To see where aristolochic acid sits among all the things that affect cancer risk, read our overview of cancer prevention and what raises cancer risk.
The bottom line
Aristolochic acid is a known human carcinogen (IARC Group 1). The most useful thing you can do is learn where exposure comes from. Then take reasonable steps to reduce it. Do not lose sleep over a single label. Put your energy into the biggest risks you can control in your own life.
Common questions
Does aristolochic acid cause cancer?
Yes. Aristolochic acid is classified as a known human carcinogen, which means there is strong evidence it can cause cancer in people. How much any one person's risk rises depends on how much they are exposed to and for how long.
How are people exposed to aristolochic acid?
Most exposure happens by taking herbal products that contain Aristolochia plants.
Which cancers are linked to aristolochic acid?
It is most strongly linked to cancers of the upper urinary tract.
How can I reduce my exposure to aristolochic acid?
The main steps are avoiding herbal products that contain Aristolochia plants.
Does a carcinogen label mean I will get cancer?
No. A classification is about hazard — whether aristolochic acid can cause cancer under some conditions — not a prediction that any one exposed person will develop cancer. Your actual risk depends on the amount and length of exposure and other factors.
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Last updated: 2026-10-02Next planned review: 2028-07-05
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Cancer Explained does not originate medical claims. Every page restates guidance already published by the National Cancer Institute, the CDC, the USPSTF and the FDA, in plain language, with the source cited so you can check the original yourself. AI does the translating and organizing; automated checks test claims, citations, clarity and safety before anything publishes, and this is translation and navigation, not clinical judgment. Nothing here is personal medical advice, and no page can account for your particular situation.
Editorial status: Source checked — This page was written with AI assistance and then compared with the sources listed on it, looking for statements those sources do not back up. That check is not a sentence-by-sentence record and can miss errors. It is not a medical review, and it does not confirm the page is complete or right for your situation.
Human medical review: not completed. Pages here are not signed off by a clinician before they publish. That is not an oversight we are quietly working around: we restate published guidance and cite it, so the authority belongs to the source rather than to us, and every page names where its claims come from — you can verify us instead of trusting us. Where a volunteer clinician has reviewed a page, their name and credentials appear on it; where no name appears, no clinician has checked it. We are glad to have reviewers and are recruiting them, and we do not hold pages back waiting for one. Use this site to understand your situation and to ask better questions of the people treating you.
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