Get emergency medical help if you have any of these signs of an allergic reaction: hives; difficult breathing; swelling of your face, lips, tongue, or throat.
Less serious side effects may include:
dizziness or headache,
a rash, or
nausea, vomiting, or stomach upset.
This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.
 Robitussin Chest Congestion side effects (more detail)
