Most people have a resting heart rate between 60 and 100 beats per minute. A 15-minute brisk walk can increase heart rate to 110 to 120 beats per minute. Tachycardia is defined as a heart rate above 100 beats per minute. Tachycardia can be a side effect of clozapine. Patients with tachycardia should discuss this with their clinician. Tachycardia from clozapine is not accompanied by pain, signs of a heart attack, shortness of breath, fever, or signs of a heart rhythm problem. Those could indicate a medical emergency.