Before you begin using a medication, be sure to inform your doctor of any medical conditions or allergies you may have, any medications you are taking, whether you are pregnant or breast-feeding, and any other significant facts about your health. These factors may affect how you should use this medication.
Anemia: Cobimetinib may cause low levels of red blood cells. If you experience symptoms of reduced red blood cell count (anemia) such as shortness of breath, feeling unusually tired, or pale skin, contact your doctor as soon as possible.
Your doctor will do blood tests regularly to monitor the number of specific types of blood cells, including red blood cells, in your blood.
Bleeding: Cobimetinib can increase the risk of experiencing uncontrolled bleeding. If you have risk factors for bleeding, such as medical conditions that reduce clotting or you are taking blood thinners, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.
Heart problems: This medication may worsen symptoms of heart disease. If you have heart disease such as angina, congestive heart failure, or arrhythmia, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed. Contact your doctor as soon as possible if you develop symptoms of heart problems such as shortness of breath, chest pain, rapid heartbeat, or swollen ankles. Your doctor may want to monitor your heart function periodically while you are using this medication, to ensure that any problems are identified early in their development.
High blood pressure: Cobimetinib may increase your blood pressure. Your doctor will monitor your blood pressure while you are taking this medication. If you have high blood pressure, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.
Liver function: Decreased liver function may cause cobimetinib to build up in the body, causing side effects. It has also been reported to cause decreased liver function. If you experience symptoms of liver problems such as fatigue, feeling unwell, loss of appetite, nausea, yellowing of the skin or whites of the eyes, dark urine, pale stools, abdominal pain or swelling, and itchy skin, contact your doctor immediately.
Your doctor may want to test your liver function regularly with blood tests while you are taking this medication. This often allows reduced liver function to be identified before it becomes too severe.
Muscle effects: Muscle damage has been associated with the use of cobimetinib. Report any unexplained muscle pain, tenderness, weakness, or cramps, or any brown or discoloured urine to your doctor immediately, particularly if you are also experiencing malaise (a general feeling of being unwell) or fever.
Sensitivity to sunlight: This medication may increase the sensitivity of the skin to sunlight, increasing the risk of sunburn. Avoid exposure to sunlight as much as possible, particularly between the hours of 10 am and 2 pm, while you are taking this medication and for 7 days after completing treatment. Wear a broad-spectrum sunscreen and lip balm with an SPF of 50 or greater. If you notice any unusual skin rash or peeling, contact your doctor immediately.
Vision: This medication may fluid to build up in the back of the eye. It may also contribute to a blockage of the blood vessels that lead out of the eye. If you notice any vision changes or problems, contact your doctor as soon as possible.
Pregnancy: This medication should not be used during pregnancy unless the benefits outweigh the risks. Cobimetinib may cause harm to a developing baby if taken by the mother. If you become pregnant while taking this medication, contact your doctor immediately. Use 2 forms of effective birth control while taking this medication and for at least 3 months after stopping treatment.
Breast-feeding: It is not known if cobimetinib passes into breast milk. If you are a breast-feeding mother and are taking this medication, it may affect your baby. Talk to your doctor about whether you should continue breast-feeding.
Children: The safety and effectiveness of using this medication have not been established for children.
Seniors: Seniors may be at an increased risk of experiencing side effects of this medication. It may be necessary to use a lower dose of this medication to reduce the severity of side effects.