In the treatment of HER2-positive breast cancer Tucaxen 150mg tablet is used. This medicine works by stopping the activity of the HER3 protein in the body. There are several side effects of this medicine which are diarrhea, fatigue, vomiting, nausea, rash, decreased appetite, hair loss, muscle pain, and joint pain. If these side effects are seen in the patient's body, no need to worry, they will go away on their own. Some side effects may be serious and require to consult a doctor.