Symptoms of overdose can be similar to the medication’s side effects, but are usually more severe. Patients exhibiting any of these symptoms should contact their physician immediately:

• Unsteadiness, tremor or convulsions of the body
• Flushing or redness of the face
• Rapid heartbeat or low blood pressure

In addition, patients experiencing antihistamine overdose may experience symptoms of the nervous system, including:

• Depression
• Nervousness
• Drowsiness
• Hallucinations
• Disorientation
• Delirium
• Seizures

For less severe symptoms that do not indicate overdose but require contacting a physician, see Potential side effects.