Crossover trial
A trial in which participants receive, in sequence, the experimental intervention, then, after a specified time, the control intervention, or vice versa.
Note 1: In this type of trial each participant serves as their own control and randomisation may be used to determine the order (or sequence) in which the participant receives the experimental and control interventions.
Note 2: Washout periods are usually included between the experimental and control phases of the trial to ensure that the effects of the first intervention do not carry over into the second phase of the trial.
Note 3: Synonyms include crossover study, and crossover design.