Many medications can cause side effects. A side effect is an unwanted response to a medication when it is taken in normal doses. Side effects can be mild or severe, temporary or permanent.

The side effects listed below are not experienced by everyone who takes Samsca (Tolvaptan). If you are concerned about side effects, discuss the risks and benefits of Samsca (Tolvaptan) with your doctor.

The following side effects have been reported by at least 1% of people taking Samsca (Tolvaptan). Many of these side effects can be managed, and some may go away on their own over time.

Contact your doctor if you experience these side effects and they are severe or bothersome. Your pharmacist may be able to advise you on managing side effects.

• Constipation
• Dry Mouth
• increased urine volume
• more frequent urination
• thirst
• weakness

Although most of the side effects listed below don't happen very often, they could lead to serious problems if you do not seek medical attention.

Check with your doctor as soon as possible if any of the following side effects occur:

• signs of dehydration (e.g., dry or sticky mouth, decreased urine production, decreased tear production, dizziness, thirst, nausea, vomiting)
• signs of liver problems (e.g., nausea, vomiting, Diarrhea, loss of appetite, weight loss, yellowing of the skin or whites of the eyes, dark urine, pale stools)
• symptoms of high blood sugar (e.g., frequent urination, increased thirst, excessive eating, unexplained weight loss, poor wound healing, infections, fruity breath odour)

Stop taking the medication and seek immediate medical attention if any of the following occur:

• signs of bleeding in the stomach (e.g., bloody, black, or tarry stools; spitting up of blood; vomiting blood or material that looks like coffee grounds)

Some people may experience side effects other than those listed. Check with your doctor if you notice any symptom that worries you while you are taking Samsca (Tolvaptan).

15 mg
Each non-scored, bevelled-edged, shallow-convex, blue, triangular tablet debossed with "OTSUKA" and "15" on one side contains 15 mg of Samsca (Tolvaptan). Nonmedicinal ingredients: corn starch, hydroxypropyl cellulose, lactose monohydrate, low-substituted hydroxypropyl cellulose, magnesium stearate, microcrystalline cellulose, and FD&C Blue No. 2 Aluminum Lake as colorant.

30 mg
Each non-scored, bevelled-edged, shallow-convex, blue, round tablet debossed with "OTSUKA" and "30" on one side contains 30 mg of Samsca (Tolvaptan). Nonmedicinal ingredients: corn starch, hydroxypropyl cellulose, lactose monohydrate, low-substituted hydroxypropyl cellulose, magnesium stearate, microcrystalline cellulose, and FD&C Blue No. 2 Aluminum Lake as colorant.

60 mg
Each non-scored, bevelled-edged, blue, modified rectangular, shallow-convex, tablet, debossed with “OTSUKA” and “60” on one side, contains 60 mg of Samsca (Tolvaptan). Nonmedicinal ingredients: corn starch, hydroxypropyl cellulose, lactose monohydrate, low-substituted hydroxypropyl cellulose, magnesium stearate, microcrystalline cellulose, and FD&C Blue No. 2 Aluminum Lake as colorant.

Do not take Samsca (Tolvaptan) if you:

• are allergic to Samsca (Tolvaptan) or any ingredients of the medication
• are allergic to benzazepine or benzazepine derivatives (e.g., Mirtazapine)
• are not producing urine
• are using certain other medications, such as itraconazole, ketoconazole, clarithromycin, HIV protease inhibitors, nefazodone
• have high levels of sodium in the blood
• have low blood sodium combined with excessive loss of body water
• urgently need to increase sodium in the body
• cannot sense or respond to thirst
• are pregnant
• are breast-feeding
• are using Samsca (Tolvaptan) for autosomal dominant polycystic Kidney Disease (ADPKD)
• have glucose-galactose malabsorption, galactose intolerance, or Lapp lactase deficiency

There may be an interaction between Samsca (Tolvaptan) and any of the following:

• angiotensin converting enzyme inhibitors (ACEIs; e.g., Captopril, Lisinopril, Ramipril)
• angiotensin receptor blockers (ARBs; e.g., Candesartan, Irbesartan, Losartan)
• Amiodarone
• Apalutamide
• Aprepitant
• "azole" antifungals (e.g., itraconazole, ketoconazole, Voriconazole)
• Baricitinib
• Bosentan
• calcium channel blockers (e.g., Amlodipine, Diltiazem, Nifedipine, Verapamil)
• Carbamazepine
• Carvedilol
• cefaclor
• ciprofloxacin
• Cimetidine
• Clofarabine
• Cobicistat
• conivaptan
• Crizotinib
• Cyclosporine
• Dabrafenib
• Deferasirox
• Desmopressin
• Digoxin
• Dronedarone
• Elagolix
• Eluxadoline
• Empagliflozin
• Enzalutamide
• Ezetimibe
• fexofenadine
• Flibanserin
• fosaprepitant
• fosphenytoin
• Furosemide
• Glyburide
• grapefruit juice
• Hepatitis C antivirals (e.g., asunaprevir, daclatasvir, grazoprevir, ledipasvir)
• HIV non-nucleoside reverse transcriptase inhibitors (e.g., delavirdine, efavirenz, etravirine, nevirapine)
• HIV protease inhibitors (atazanavir, darunavir, lopinavir, ritonavir)
• Idelalisib
• imatinib
• Irinotecan
• Lapatinib
• letermovir
• lumacaftor
• macrolide antibiotics (e.g., clarithromycin, erythromycin)
• Methotrexate
• mifepristone
• Mitotane
• Modafinil
• mycophenolate
• Nilotinib
• Palbociclib
• Pazopanib
• penicillin
• Phenobarbital
• Phenytoin
• Pimozide
• potassium-sparing diuretics (water pills; e.g., Amiloride, Spironolactone, triamterene)
• primidone
• Repaglinide
• quinidine
• quinine
• rifabutin
• rifampin
• St. John's wort
• Sarilumab
• siltuximab
• sodium chloride
• "statin" anti-cholesterol medications (e.g., Atorvastatin, Lovastatin, Simvastatin)
• Stiripentol
• Sulfasalazine
• Tacrolimus
• Tocilizumab
• Topotecan
• zidovudine

If you are taking any of these medications, speak with your doctor or pharmacist. Depending on your specific circumstances, your doctor may want you to:

• stop taking one of the medications,
• change one of the medications to another,
• change how you are taking one or both of the medications, or
• leave everything as is.

An interaction between two medications does not always mean that you must stop taking one of them. Speak to your doctor about how any drug interactions are being managed or should be managed.

Medications other than those listed above may interact with Samsca (Tolvaptan). Tell your doctor or prescriber about all prescription, over-the-counter (non-prescription), and herbal medications you are taking. Also tell them about any supplements you take. Since caffeine, alcohol, the Nicotine from cigarettes, or street drugs can affect the action of many medications, you should let your prescriber know if you use them.

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 Samsca (Tolvaptan).

Dehydration: Samsca (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.

Diabetes: Samsca (Tolvaptan) may cause an increase in blood sugar levels (may cause a loss of blood glucose control) and glucose tolerance may change. People with diabetes may find it necessary to monitor their blood sugar more frequently while using Samsca (Tolvaptan).

If you have diabetes or are at risk for developing diabetes, discuss with your doctor how Samsca (Tolvaptan) may affect your medical condition, how your medical condition may affect the dosing and effectiveness of Samsca (Tolvaptan), and whether any special monitoring is needed.

Fluid and electrolyte balance: Samsca (Tolvaptan) may cause the levels of electrolytes such as potassium, magnesium, chloride, and calcium in the blood to change while taking Samsca (Tolvaptan). 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 Samsca (Tolvaptan).

Galactose intolerance/glucose malabsorption: Samsca (Tolvaptan) medications are prepared with lactose. If you have lactose or galactose intolerance you should not take these medications.

Grapefruit juice: Grapefruit juice affects how Samsca (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 any time while taking Samsca (Tolvaptan) for treatment.

Liver function: Samsca (Tolvaptan) may reduce liver function and can cause liver failure. If you have liver problems, discuss with your doctor how Samsca (Tolvaptan) may affect your medical condition, how your medical condition may affect the dosing and effectiveness of Samsca (Tolvaptan), and whether any special monitoring is needed. Your doctor may want to test your liver function regularly with blood tests while you are taking Samsca (Tolvaptan). 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.

Samsca (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: Samsca (Tolvaptan) should not be used during. If you become pregnant while taking Samsca (Tolvaptan), contact your doctor immediately.

Breast-feeding: It is not known if Samsca (Tolvaptan) passes into breast milk. If you are a breast-feeding mother and are taking Samsca (Tolvaptan), it may affect your baby. Women who are taking Samsca (Tolvaptan) are advised to not breast-feed.

Children: The safety and effectiveness of using Samsca (Tolvaptan) have not been established for children.