Dimetapp Cold is a medication that is used for relieving the symptoms of a cold such as coughing and nasal congestion. It contains the active ingredient dextromethorpan, which works as a cough suppressant. The other active ingredient is phenylpropanolamine and it works as a nasal decongestant. This medication does have a few side effects, such as drowsiness and dizziness, but is regarded as safe for most adults. However, some individuals should not take Dimetapp Cold including people who have liver or kidney disease, diabetes, heart problems, high blood pressure or emphysema.