Other diet products, especially diet teas, are based on laxatives and diuretics. These are controversial because they may only produce temporary, illusory weight loss through dehydration. Like anything which causes water loss from the body, they can deplete electrolytes and potentially cause cardiovascular problems including increases in blood pressure. Obese people who suffer from hypertension would have more risk than the general population, but daily use of stimulant laxatives is a bad idea. Some feel it's safe for most people, others see no point in taking any risk if other herbs can offer similar benefits.
Roots have more alkaloid than leaves, and young leaves more than older leaves.
Chaparral - also implicated as a liver toxin, but without strong evidence. Reported cases of human toxicity are complicated and rare, no liver toxic compounds have been identified, and the FDA, which has done some feeble testing with cultured liver cells but no classic toxicology testing, has been unable to come up with compelling evidence of harm. Ephedra - after over 5,000 years of human use, the herb is controversial because of abuse in diet and energy products and the use of strong concentrates in products. Some products contain synthetic ephedrine, just like asthma drugs. Weight loss from such products may be mostly by dehydration, hence not lasting.