Guaifenesin is the active ingredient in several common expectorants, including Mucinex and Robitussin ... phenylephrine have the initials PE added to the name (e.g., Sudafed PE).

Guaifenesin is the active ingredient in several common expectorants, including Mucinex and Robitussin. It is a safe and effective ... Some products containing phenylephrine have the initials PE added ...

Robitussin was at the center of a class-action complaint over its “non-drowsy” cough and cold medicines. Screengrab from Calchi, et al. v. GlaxoSmithKline Consumer Healthcare Holdings (US) LLC ...