New cancer drugs that can be taken orally allow patients to take their medication at home, making treatment significantly more convenient. However, moving treatment out of the controlled hospital environment increases the risk of medication mistakes. A review found that 20% to 80% of patients taking oral cancer drugs deviated from the correct dose. Problems included both underadherence (taking less medication than prescribed) and overadherence (taking too much medication). Reasons for overadherence included patients continuing to take their medication during 'rest cycles' intended to be drug-free or overcompensating for missed doses. Under- and overadherence were more likely in patients with complex drug regimens. Overadherence was associated with more side effects, while underadherence decreased side effects, but risked undermining the effectiveness of the cancer treatment.