It is not common at regular doses, but some people may become dizzy, drowsy or may experience blurred vision when orally consuming Robitussin DM elixir, according to Drugs.com. These side effects can be intensified if a person mixes other medications with Robitussin DM elixir or if they consume alcohol before or after taking this medicine.
People should not perform complex tasks or drive if they are not familiar with the common side effects of Robitussin DM elixir, according to Drugs.com. Severe side effects such as tightness in the chest and difficulty breathing are rare but can occur if the person taking Robitussin Elixir DM is allergic to the medication. Robitussin DM elixir is an expectorant and cough suppressant that is commonly used to reduce symptoms associated with bronchitis, colds and sore throats.