I'm a 22 year old girl who weighs 118. can i take sudafed 12 hour and mucinex (guaifenesin) at the same time?

Cold Medicines: Yes, sudafed can be taken with mucinex (guaifenesin). Sudafed is a decongestant, to help nasal congestion( stuffiness). Possible side effects include rapid heart beat, a shaky feeling or difficulty sleeping. Mucinex (guaifenesin) is an expectorant. It helps to clear out thick secretions from the sinuses and airways. If your symptoms last more than two weeks or include persistent fever, then see your family physician.

Yes: Sudafed is an Alpha agonist and as such constricts blood vessels in the nose to open the nasal airway. Mucinex (guaifenesin) is used to liquify secretions and make them easier to handle. They are 2 different drugs, do not cross react and have totally different mechanisms of action. You can safely take them. But remember that sudafed can raise blood pressure and increase heart rate.