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. Stimulant diet teas - mostly ephedra, caffeine sources and sometimes willow or aspirin. They probably are appetite suppressants, and may stimulate fat burning. Some individuals should not touch them, for others there are questions about safety and healthfulness. Hemp - more products are appearing using the seed oil, which lacks the intoxicating components of the plant, also known as marijuana.