It is important that your doctor check your progress at regular visits to allow changes in your dose and to check for any unwanted effects.
If you develop any unusual or strange thoughts and behavior while receiving biperiden, be sure to discuss it with your doctor. Some changes that have occurred in people receiving this medicine are like those seen in people who drink too much alcohol. Other changes might be confusion, worsening of depression, visual hallucinations (seeing things that are not there), suicidal thoughts, and unusual excitement, nervousness, or irritability.
Biperiden may cause drowsiness, trouble with controlling movements, or trouble with thinking or seeing clearly. Make sure you know how you react to this medicine before you drive, use machines, or do other jobs that require you to be alert, well-coordinated, or able to think or see well.
This medicine will add to the effects of alcohol and other CNS depressants (medicines that make you drowsy or less alert). Some examples of CNS depressants are antihistamines or medicine for hay fever or colds; sedatives, tranquilizers, or sleeping medicine; prescription pain medicine or narcotics; barbiturates or medicine for seizures; muscle relaxants; or anesthetics, including some dental anesthetics. Check with your doctor before taking any of the above while you are taking this medicine.