Codeine (codeine phosphate) contains the active ingredient codeine and is used to reduce pain from headache, the flu and common cold. See here for more information and to order.
A: Mucinex contains the active ingredient guaifenesin, which is an expectorant that helps loosen phlegm and thin bronchial secretions. Mucinex does not have rapid heart rate as a possible side effect. There is a product called Mucinex-D that contains pseudoephedrine, and this ingredient can increase heart rate.
Summary: Drowsiness is found among people who take Mucinex, especially for people who are female, 50-59 old, have been taking the drug for. Personalized health information: on eHealthMe you can find out what patients like me (same gender, age) reported their drugs and conditions on FDA and social media since 1977.