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.
Dehydration: Tolvaptan causes an increase in the amount of urine produced as it causes the body to eliminate fluid. As a result, it is possible for dehydration to occur. Drink fluids when you feel thirsty and be aware of other signs of dehydration such as muscle cramps, nausea and vomiting, rapid pounding heart beat as well as a feeling of dry stickiness in the mouth.
Fluid and electrolyte balance: Tolvaptan may cause the levels of electrolytes such as potassium, magnesium, chloride, and calcium in the blood to change while taking this medication. If you experience symptoms of fluid and electrolyte imbalance such as muscle pains or cramps; dry mouth; numb hands, feet, or lips; or racing heartbeat, contact your doctor as soon as possible. Your doctor will do blood tests regularly to monitor the levels of these electrolytes in your blood while you are taking this medication.
Grapefruit juice: Grapefruit juice affects how tolvaptan is removed from the body and may cause too much of the medication to build up in the body and cause possibly harmful side effects. Do not drink grapefruit juice or eat grapefruit at anytime while taking this medication for treatment.
Liver function: Tolvaptan may reduce liver function and can cause liver failure. If you have liver problems, 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. Your doctor may want to test your liver function regularly with blood tests while you are taking this medication. 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.
Tolvaptan may increase the risk of bleeding in the stomach when it is taken by people with liver disease. If you experience signs of bleeding in the digestive system, such as blood in the stools, vomiting blood or a substance that looks like coffee grounds, or black and tarry stools get immediate medical help.
Rapid correction of sodium levels: Correcting the blood levels of sodium too quickly can be as dangerous as having too little sodium in the body. This may be more likely to occur if you consume large amounts of alcohol, are severely malnourished, or have advanced liver disease. If you experience difficulty speaking, confusion, drowsiness, mood changes, difficulty swallowing, or weakness in the arms and legs, contact your doctor immediately.
Pregnancy: This medication should not be used during pregnancy unless the benefits outweigh the risks. If you become pregnant while taking this medication, contact your doctor immediately.
Breast-feeding: It is not known if tolvaptan 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.