Health officials have issued an urgent warning for more than two dozen supplements because they may contain poisonous ingredients.

The FDA alert covers 29 supplement brands that claim to contain tejocote (Crataegus mexicana) root or Brazil seed, which are high in vitamin C and other antioxidants. Limited evidence suggests they may promote weight loss.

However, an FDA analysis found the supplements actually contain yellow oleander instead of the labeled ingredients. 

Yellow oleander, also called Thevetia peruviana, is a poisonous plant native to Mexico and Central America 'and a toxic substance of concern to public health officials,' the FDA said. 

The agency warned yellow oleander may lead to neurologic, gastrointestinal and cardiovascular adverse health effects, which could be severe or even fatal. These include cardiac arrest, abdominal pain and confusion, among others. 

Products in question were sold online on Amazon, eBay and Etsy, as well as independent websites. 

The FDA has advised consumers to immediately stop using the products and dispose of them.  

Several companies have recalled the products, while others have removed them or declined to issue a recall. A full list of implicated products can be found below.  

'The FDA advises consumers who have taken any of these products to contact their health care provider immediately, even if the products have not been used recently, so that an appropriate evaluation may be conducted,' the FDA said. 

The agency also urged consumers to call 911 or get emergency medical help immediately 'if you or someone in your care has serious side effects from these products.'

Consumers can also contact their state's poison control center. 

The FDA said it is continuing to identify and test suspect products. 

The efforts began in September 2023, when the CDC published a report of tejocote root products found to actually contain yellow oleander. 

The FDA said: 'Based on the FDA’s sampling and testing results thus far, the FDA is also concerned that other products marketed as tejocote root (including with other names such as Crataegus mexicana, Raiz de Tejocote and Mexican Hawthorn) may contain yellow oleander. 

'Consuming yellow oleander can cause severe adverse health effects and be potentially fatal.'

Yellow oleander in these products is meant to substitute for tejocote root or Brazil seed because its toxins can cause extreme nausea, diarrhea and vomiting, resulting in rapid, unhealthy weight loss. 

The poison also suppresses appetite.

Yellow oleander seeds also look similar to natural products like candlenuts (Nuez de la India).  

Tejocote root and Brazil seed are thought to aid in weight loss, but there is limited evidence pointing to this benefit.