This information is generalized and not intended as specific medical advice. Consult your healthcare professional before taking or discontinuing any drug or commencing any course of treatment.
Serious. These medicines may interact and cause very harmful effects. Contact your healthcare professional (e.g. doctor or pharmacist) for more information.
How the interaction occurs:
Both of these medicines increase the amount of salt (sodium) in your blood.
What might happen:
Although not having enough sodium in your blood can be serious, raising the amount of sodium in your blood too quickly can cause a serious side effect called osmotic demyelination syndrome (ODS), which can be fatal.
What you should do about this interaction:
Make sure your healthcare professionals (e.g. doctor or pharmacist) know that you are taking these medicines together. Let your doctor know if you have a history of liver problems or alcoholism, or if you have not been eating well/enough lately. These conditions can increase your risk of ODS. Let your doctor know right away if you experience trouble speaking/swallowing, mental/mood changes (such as confusion or drowsiness), weakness/involuntary movement in the arms/legs, and/or seizures.Your healthcare professionals may already be aware of this interaction and may be monitoring you for it. Do not start, stop, or change the dosage of any medicine before checking with them first.
1.Samsca (tolvaptan) US prescribing information. Otsuka Pharmaceutical Co., Ltd. February, 2014.
2.Vaprisol (conivaptan hydrochloride) US prescribing information. Astellas Pharma US, Inc. February, 2012.