Before you begin using a medication, be sure to inform your doctor of any medication 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: Bosentan can reduce the number of red blood cells, which carry oxygen throughout your body, and make you feel tired. Your doctor will periodically do blood work to monitor your red blood cell levels to ensure that this does not happen.
Heart failure: People with severe chronic heart failure may see a worsening of their condition when they first start bosentan. This may be due to fluid retention, which is one of the side effects of bosentan. If you have severe chronic heart failure, 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 problems: Bosentan can affect your liver. Your doctor will perform regular blood tests to make sure your liver is functioning properly. Bosentan should not be used by people who have moderately to severely reduced liver function.
Low blood pressure: If you have low 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.
Stopping medication: Suddenly stopping bosentan may worsen your symptoms. Do not stop taking this medication unless directed by your doctor. If you are stopping treatment, your doctor will monitor you and reduce the dose over a period of time before stopping the medication completely.
Pregnancy: The medication should not be used during pregnancy, as it can cause serious harm to the fetus. Your doctor should perform a pregnancy test before you start this medication, and monthly thereafter while you are taking this medication. Since bosentan decreases the effectiveness of hormonal birth control, you should use more than one form of contraception (e.g., a non-hormonal forms such as condoms) while taking this medication. If you become pregnant while taking this medication, contact your doctor immediately.
Breast-feeding: It is not known if bosentan 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 in children are not well established. Your doctor will determine if the benefits of the medication outweigh the risks for your child.