Solifenacin belongs to the family of medications known as antispasmodics. It is used to relieve symptoms associated with an overactive bladder, such as urinary urgency (a need to urinate right away), urinary frequency, and urge incontinence (leaking or wetting caused by an unstoppable urge to urinate).

This medication works by relaxing the bladder. It helps to reduce bladder spasms, the urge to pass urine, and the frequency of urination.

It is usually necessary to take this medication for at least 4 weeks before you can expect maximum benefit from the treatment.

This medication may be available under multiple brand names and/or in several different forms. Any specific brand name of this medication may not be available in all of the forms or approved for all of the conditions discussed here. As well, some forms of this medication may not be used for all of the conditions discussed here.

Your doctor may have suggested this medication for conditions other than those listed in these drug information articles. If you have not discussed this with your doctor or are not sure why you are taking this medication, speak to your doctor. Do not stop taking this medication without consulting your doctor.

Do not give this medication to anyone else, even if they have the same symptoms as you do. It can be harmful for people to take this medication if their doctor has not prescribed it.

The recommended dose of solifenacin is 5 mg once daily. If there are few side effects with a 5 mg dose, the dose can be increased to 10 mg once daily.

If you have severe kidney function impairment or moderate liver function impairment, or if you are taking certain medications (e.g., ketoconazole, clarithromycin, diclofenac,  verapamil), doses above 5 mg daily are not recommended.

Solifenacin should be taken with liquids and swallowed whole. It may be taken with or without food.

Many things can affect the dose of a medication that a person needs, such as body weight, other medical conditions, and other medications. If your doctor has recommended a dose different from the ones listed here, do not change the way that you are taking the medication without consulting your doctor.

It is very important to take this medication exactly as prescribed. If you miss a dose of this medication, take your next dose at the usual time. Do not take a double dose to make up for a missed one. If you are not sure what to do after missing a dose, contact your doctor or pharmacist for advice.

Store this medication at room temperature and keep it out of the reach of children.

Do not take solifenacin if you:

• are allergic to solifenacin or to any of the ingredients of the medication
• are dependent on dialysis
• have gastroparesis (delayed emptying of the stomach)
• have narrow-angle glaucoma
• have urinary retention (an inability to empty the bladder)

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 this medication. If you are concerned about side effects, discuss the risks and benefits of this medication with your doctor.

The following side effects have been reported by at least 1% of people taking this medication. 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.

• blurred vision
• constipation
• dry eyes
• dry mouth
• headache
• heartburn
• nausea
• upper abdominal pain

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

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

• constipation for more than 3 days
• severe abdominal pain
• swelling of the feet, ankles, or lower leg

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

• fast or irregular heartbeat
• inability to urinate
• signs of a severe allergic reaction (e.g., hives; difficulty breathing; or swelling of the mouth, lips, tongue, or throat)

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 this medication.

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.

Abnormal heart rhythm: Solifenacin may cause a heart rhythm disturbance called QT prolongation. If you have a history of QT prolongation or are taking certain medications (e.g., amiodarone, sotalol), 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.

Bladder outflow obstruction: If you have a medical problem that obstructs the flow of urine from the bladder (e.g., enlarged prostate, prostate cancer), this medication may make you unable to urinate. If you have a problem with urinary flow, 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.

Blurred vision: Solifenacin may cause blurred vision. Avoid activities such as driving, operating machinery, or performing hazardous work until you know how solifenacin affects your vision.

Gastrointestinal disorders: Solifenacin can slow movement through the gastrointestinal tract. If you have decreased gastrointestinal movement caused by a medical problem (e.g., diabetes), surgery, or medications, 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.

Heat stroke: Solifenacin causes a decrease in sweating, which is one of the body's way of cooling off. When solifenacin is taken during very hot weather, it can cause fever and heat stroke due to the body being unable to cool down enough. Take care not to overheat when you are taking this medication. Stay in a cool environment if possible, limit the length of time you spend outdoors, and drink plenty of water to reduce the risk of heat stroke.

Kidney function: If you have reduced kidney function or kidney disease, 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. If you have severe kidney function impairment, do not take daily doses greater than 5 mg of solifenacin.

Liver function: The liver is responsible for removing solifenacin from the body. If the liver is not working well, the medication can build up in the body, causing unwanted side effects. If you have reduced liver function or liver disease, 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.

If you have moderate liver function impairment, do not take daily doses greater than 5 mg of solifenacin, and have your doctor monitor your condition closely. Do not take solifenacin if you have severe liver function impairment.

Pregnancy: This medication should not be used during pregnancy unless the benefits outweigh the risks. Women of childbearing age should talk to their doctor about whether birth control is appropriate. If you become pregnant while taking this medication, contact your doctor immediately.

Breast-feeding: It is not known if solifenacin passes into breast milk. If you are breast-feeding 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.

There may be an interaction between solifenacin and any of the following:

• aclidinium
• amantadine
• amiodarone
• anagrelide
• antihistamines (e.g., cetirizine, chlorpheniramine, dimenhydrinate, diphenhydramine)
• apalutamide
• aprepitant
• atazanavir
• antipsychotics (e.g., chlorpromazine, haloperidol, clozapine, quetiapine, risperidone)
• atropine
• azole antifungals (e.g., fluconazole, itraconazole, ketoconazole, voriconazole)
• benztropine
• botulinum toxin
• cannabis
• cobicistat
• codeine
• cyclobenzaprine
• cyclopentolate
• darifenacin
• dicyclomine
• diltiazem
• disopyramide
• domperidone
• donepezil
• doxepin
• dronedarone
• enzalutamide
• fentanyl
• fesoterodine
• galantamine
• glucagon
• glycopyrrolate
• grapefruit juice
• HIV non-nucleoside reverse transcriptase inhibitors (NNRTIs; e.g., , efavirenz, etravirine, nevirapine)
• HIV protease inhibitors (e.g., darunavir, fosamprenavir, lopinavir, saquinavir, tipranavir)
• hyoscyamine
• ipratropium
• macrolide antibiotics (e.g., clarithromycin, erythromycin)
• methadone
• methylene blue
• metoclopramide
• mifepristone
• mirabegron
• mitotane
• modafinil
• monoamine oxidase inhibitors (e.g. moclobemide, selegiline)
• nabilone
• narcotic medications (e.g., morphine, codeine)
• neostigmine
• netupitant
• nitroglycerin
• orphenadrine
• oxybutynin
• potassium chloride, potassium supplements
• pizotifen
• procainamide
• propiverine
• protein kinase inhibitors (e.g., crizotinib, fedratinib, imatinib)
• prucalopride
• pyridostigmine
• quinine
• rifampin
• rilpivirine
• rivastigmine
• St. John's wort
• scopolamine
• seizure medications (e.g., carbamazepine, phenobarbital, phenytoin)
• sotalol
• tiotropium
• thiazide diuretics (e.g., hydrochlorothiazide, indapamide)
• tocilizumab
• tolterodine
• topiramate
• trazodone
• trihexyphenidyl
• trospium
• tricyclic antidepressants (e.g., amitriptyline, desipramine, nortriptyline)
• umeclidinium
• verapamil

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 this medication. Tell your doctor or prescriber about all prescription, over-the-counter (non-prescription), and herbal medications that you are taking. Also tell them about any supplements you take. Since caffeine, decongestants, 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.