Aristolochic Acids and Bladder Cancer

Written by Regina Boyle Wheeler
Medically Reviewed by Laura J. Martin, MD on June 29, 2025
6 min read

Smoking is one of the biggest risk factors for bladder cancer. But did you know there could be another culprit sitting in your medicine cabinet? 

It’s called aristolochic acid (AA), an ingredient found mainly in herbal remedies and traditional Chinese medicine.

"Aristolochic acids are a classic example of how something labeled ‘natural' can be deceptively harmful," says Sandeep Nayak, director of the Department of Surgical Oncology at Fortis Hospital in Bangalore, India. Nayak is a pioneer in laparoscopic surgery for cancer.

They are acids found in nature in many types of plants of the aristolochia genus. These include: 

  • Birthwort
  • Pipevines 

They're also found in asarum (wild ginger) species. 

For centuries, concoctions with AA have been used to treat a variety of ailments, especially in Asian countries. Birthwort’s flower is shaped like a uterus and is traditionally used during childbirth. 

Aristolochic acid is also used for weight loss, menstrual problems, and arthritis. 

“Scientists now know that AA can bind to DNA and leave a very specific fingerprint of mutations that is strongly linked to cancers of the upper urinary tract and, to a lesser extent, bladder cancer,” says Daniel Spratt, MD, chair and professor of the Department of Radiation Oncology at Case Western Reserve University in Cleveland, Ohio. 

“The DNA damage it causes is not reversible,” Nayak says. 

One landmark study linked AA exposure to a 40%-50% lifetime risk of developing upper tract urothelial carcinoma in some regions, says Ian Udell, MD, a urologic surgeon at Beacon Clinic in Coeur d’Alene, Idaho. Urothelium is the lining of the urinary tract.

The International Agency for Research on Cancer classifies AAs as Group 1 carcinogens, which means they can cause cancer in people. 

AA also has been linked to serious kidney scarring. Aristolochic acid nephropathy “causes the kidneys to shrink and fail over time. Many patients who have this kidney damage later go on to develop tumors in the lining of the kidneys, ureters, or bladder,” Spratt says. 

Aristolochic acid nephropathy was first identified in patients treated at a weight loss clinic in Belgium in 1991. Doctors started to see several cases of women with serious or near end-stage kidney disease who had been on weight loss plans that included AA supplements. 

AA nephropathy causes kidney function to get worse quickly – sometimes in six months to two years. There is no treatment, but transplants are an option for people with end-stage kidney disease. 

Nayak recently treated a 52-year-old woman who had been using unregulated weight loss teas for years. She had an unusual case of upper tract urothelial cancer and kidney damage. 

"She wasn't a smoker, had no industrial exposure, and no genetic predisposition," Nayak says.

"It was only after detailed history-taking that we discovered her daily herbal tea use, which was later found to contain traces of aristolochia."

Balkan endemic nephropathy (BEN)

Another similar kidney problem linked to AA is seen in the Balkan countries of Serbia, Croatia, Bosnia-Herzegovina, Romania, and Bulgaria. But Balkan endemic nephropathy (BEN) gets worse slowly – generally over the course of 10 to 20 years. 

This disease was first described in the 1950s, mainly in farming communities along the Danube river. BEN “is thought to be due to contaminated grain,” says Lee Richstone, MD, chair of urology at Northwell Lenox Hill Hospital in New York. 

How does that happen? 

A weed called Aristolochia clematitis is to blame. The plant’s seeds contain aristolochic acid, which gets mixed in with wheat during harvesting. It gets into flour that's made from the wheat and is then eaten, he says. 

The good news is there have been fewer BEN cases reported over the last few decades partly due to major improvements in farming and milling practices. 

Udell says to watch out for these potential dangers: 

Herbal products. Especially those labeled with “fangchi,” “mu tong,” “guang fang ji,” or “madouling.” These may be found in teas or capsules marketed for detox, weight loss, or pain relief.  

Imported supplements. Some traditional medicines, particularly from East Asia, may still contain AA despite global health warnings. 

Unregulated online products. Supplements sold online or at informal markets may not list AAs on the label – even if they are present. 

The FDA has issued an import alert that allows border officials to stop supplements containing AA, but online sales can still slip through, Spratt says. 

Dietary supplements are not regulated by the FDA like regular foods and medicines. So you’ll have to do some detective work before you decide to take anything. 

Udell suggests that buyers should beware and take precautions: 

Avoid herbal supplements with unknown ingredients. This is especially true if they come from unverified sources. 

Stick with trusted sources for any alternative or complementary treatments. Even “natural” doesn’t always mean safe. 

“If you buy herbal products, look for companies that submit to third-party quality testing, and discuss any supplement with your doctor or pharmacist, especially if you have a history of kidney disease or urinary-tract cancer,” Spratt says. 

Richstone says: “For the average person who is not from the Balkans nor dabbling in traditional Chinese medicine, then my assessment is that the risk (from aristolochic acid) is extraordinarily low.” 

“These are not common organic materials that we are exposed to in everyday life,” he adds. 

Aristolochic acid can cause cancer of the upper urinary tract and bladder cancer, too. 

It can cause kidney disease and failure (AA nephropathy) in people who take it in herbal supplements and traditional Chinese medicine. 

Avoid any dietary supplements that may contain aristolochic acid. If you don’t know, ask your pharmacist or health care provider. 

What is the use of aristolochic acid?

It’s used in traditional Chinese medicine and herbal remedies used to treat or help a variety of health conditions including: 

  • Arthritis 
  • Childbirth issues
  • Gout
  • Snakebites
  • Menstrual problems 
  • Weight loss 

Does ginger contain aristolochic acid?

The short answer is no, Udell says. 

The common ginger you buy at the grocery store or farmer’s market – Zingiber officinale – does not contain aristolochic acid.

But the plant known as wild ginger (asarumspecies, especially Asarum canadense or Asarum europaeum) can contain aristolochic acid. 

“If you’re using the standard grocery store ginger, you’re in the clear – no aristolochic acid. But if you’re out foraging or experimenting with wild ginger in herbal concoctions, do your research and be careful. In this case, wild doesn’t always mean safe,” Udell says. 

What is aristolochic acid also known as?

Herbal products are often labeled with ingredients like “fangchi,” “mu tong,” “guang fang ji,” or “madouling.” 

Be wary of supplements marketed as "kidney detox" or "natural aphrodisiacs.” They're common culprits, Nayak says. 

If you are unsure, check with your doctor about whether a specific dietary supplement is safe for you.