Among one of the biggest potential pitfalls of sassafras is its reported link with cancer. The FDA banned sassafras use in 1979 following research that showed it caused cancer in rats. "While the amount of sassafras that could potentially cause cancer in humans remains unknown, one cup of strong sassafras tea is reported to contain as much as 200 mg of safrole, an amount that is four times higher than the amount considered potentially hazardous to humans if consumed regularly," claims Blue Shield.
The U.S. National Library of Medicine's MedLine Plus website also discusses the potential problems that can arise due to sassafras overdose. When too much oil is consumed, poisoning can take place. This is when hallucinations, heart palpitations and other concerns can come in. MedLine even indicates serious ramifications are possible from overdose. "Sassafras oil is considered very toxic. Survival past 48 hours is usually a good sign that recovery will occur. If damage to the kidneys has occurred, it may take several months to heal."