The U.S. Food and Drug Administration (FDA) is warning against the use of homeopathic teething tablets after lab analysis found inconsistent amounts of belladonna, a toxic substance that could post a risk to infants and children who consume it. Standard Homeopathic Company, the manufacturer behind Hyland’s homeopathic teething products, has not agreed to conduct a recall despite the FDA’s findings.

The substance of concern is belladonna, which could cause seizures, excessive sleepiness, muscle weakness and skin flushing in children. The FDA recommends that consumers stop using the products marketed by Hyland’s and dispose any that they may have.

“The body’s response to belladonna in children under two years of age is unpredictable and puts them at unnecessary risk,” Janet Woodcock, M.D., director of the FDA’s Center for Drug Evaluation and Research, said in a press release. “We recommend that parents and caregivers not give these homeopathic teething tablets to children and seek advice from their health care professional for safe alternatives.”

The FDA issued a similar warning in September over teething tablets and gels distributed by CVS, Hyland’s and others sold online and in stores. Homeopathic teething products have not been evaluated or approved by the FDA for safety or effectiveness, and the agency is unaware of any proven health benefit of the products.

In November, Raritan Pharmaceuticals Inc recalled three belladonna-containing homeopathic products, two of which were marketed by CVS Health Corp.

Reuters contributed to this report.