During his turn, investigator A "gives a sedative" to investigator B (to eliminate a trauma) who has yet to take her turn. Thus, investigator B "cannot move" that turn. However, can she still do an action phase?

I guess. It should state otherwise on the card if not able I think…

What cause investigator B to get the "cannot move" condition?

Quatro said:

Sedative says, last line "He may not move during his next turn."

I see. Thanks.