Sweet broom (Genista x spachianus) is mildly poisonous. It belongs to the legume family (Fabaceae), and like many plants in this family, it contains an alkaloid called cytisine that can cause symptoms similar to nicotine poisoning if ingested. That said, fatal poisonings from broom plants are rare in both humans and animals.
What Makes Sweet Broom Toxic
The concerning compound in sweet broom is cytisine, a naturally occurring alkaloid found across the legume family, including the closely related Scotch broom and laburnum (golden chain tree). Cytisine acts on the same receptors in the body that nicotine does. In fact, it’s used as a smoking cessation aid in parts of Eastern Europe precisely because it mimics nicotine’s effects at lower intensity.
The problem comes with dose. When enough plant material is eaten, cytisine overstimulates the nervous system. Symptoms of poisoning mirror nicotine overdose: nausea, vomiting, dilated pupils, rapid heart rate, general weakness, and in severe cases, convulsions or difficulty breathing. All parts of the plant contain the alkaloid, though concentrations vary. Seeds and flowers tend to carry higher amounts than leaves or stems.
Risk to Dogs, Cats, and Other Pets
Broom plants as a group are considered toxic to dogs and cats. A pet that chews on sweet broom may experience vomiting, drooling, or diarrhea. More serious neurological symptoms like tremors or coordination problems are possible with larger amounts, though this is uncommon since the bitter taste tends to discourage animals from eating much.
If your dog or cat has chewed on sweet broom, watch for vomiting or unusual lethargy in the hours afterward. Small nibbles rarely cause more than mild stomach upset, but a pet that has consumed a significant quantity of flowers or seeds warrants a call to your veterinarian or a pet poison hotline.
Risk to Horses and Livestock
Grazing animals occasionally encounter broom plants in pastures or along fence lines. Colorado State University’s poisonous plant database notes that fatalities from broom ingestion in livestock are rare. Horses and cattle generally avoid the plant because of its taste, but animals with limited forage options may eat enough to develop symptoms. The signs are similar to those in smaller animals: digestive upset, increased heart rate, and in unusual cases, muscle tremors.
Risk to Humans
For adults, accidentally swallowing a small amount of sweet broom is unlikely to cause serious harm. Children are more vulnerable because of their smaller body weight, and the bright yellow flowers can be attractive to curious toddlers. If a child eats any part of the plant, contact poison control even if no symptoms appear immediately, since nausea and vomiting can take an hour or more to develop.
It’s worth noting that a different tropical plant called sweet broom or “licorice weed” (Scoparia dulcis) shares the common name but is an entirely different species. That plant has been studied for medicinal use and shows remarkably low toxicity. In laboratory testing, oral doses as high as 8 grams per kilogram of body weight in mice produced no deaths and no changes in behavior. If you’re growing Scoparia dulcis rather than Genista, the toxicity risk is minimal. The two plants look nothing alike: Genista is a shrubby ornamental with clusters of yellow flowers, while Scoparia dulcis is a small, upright herb with tiny white blooms.
What To Do After Accidental Ingestion
For people, call your local poison control center. They’ll ask what part of the plant was eaten, how much, and whether symptoms have started. Don’t induce vomiting unless specifically instructed to do so.
For pets, contact your veterinarian or an animal poison helpline. Try to estimate how much was consumed and note the time. Bringing a photo or sample of the plant helps with identification, since several broom species look similar and share common names.
In both humans and animals, treatment is supportive. There’s no specific antidote for cytisine, but the body clears the alkaloid relatively quickly, with a half-life of about five hours. Most cases resolve with monitoring and management of symptoms like nausea or elevated heart rate. Severe poisoning requiring medical intervention is uncommon with sweet broom because the plant’s cytisine concentration is lower than that of some relatives like laburnum, where the seeds pack a much heavier dose.