Solifenacin (Vesicare): overactive bladder explained

Solifenacin treats an overactive bladder: a sudden, urgent need to pass urine, needing to go more often than usual, and not being able to hold urine until you reach the toilet. It is available only on prescription, as tablets and as a liquid.

Brand names the NHS lists are Vesicare for solifenacin alone and Vesomni and Vecit for products that combine solifenacin with tamsulosin for men with prostate-related urgency.

Solifenacin relaxes the muscles in the bladder wall so the bladder can hold more liquid, which means you do not need to pass urine as often or as urgently. It is classed as an antimuscarinic, or anticholinergic.

It starts to work within 3 to 8 hours, but it can take 4 to 6 weeks to work fully, so judging the benefit too early can be misleading. That is why the first review is at 4 to 6 weeks.

The standard dose the NHS gives is 5 mg once daily, with a maximum of 10 mg if symptoms do not improve; the combined tablet is one a day. Take it at the same time each day, with or without food. The liquid is 5 mg per 5 ml, measured with the syringe or spoon supplied.

Treatment is usually long-term, with reviews every 6 to 12 months. The NHS also advises pelvic floor muscle training and bladder training alongside it.

• If you miss a dose, take it when you remember unless the next day has arrived; then skip it. Never double up.

• One extra dose is unlikely to harm. Dry mouth and headache can follow an overdose.

• Fast heartbeat, breathing problems or seizures after too much need 999; hallucinations or being unable to pass urine need NHS 111.

Most adults aged 18 and over can take it. Tell your doctor if you have had an allergic reaction to solifenacin or any medicine; liver or kidney problems; myasthenia gravis; glaucoma, because it can raise eye pressure; a severe stomach or bowel condition, including toxic megacolon, a rare complication of ulcerative colitis or Crohn's disease; or if you cannot pass urine or empty the bladder completely. Also mention pregnancy, trying for a baby or breastfeeding.

Common effects are dry mouth, headache, nausea, constipation, bloating or indigestion, stomach pain and blurred vision. Sugar-free gum or sweets ease dry mouth, and fibre, water and exercise help constipation. If your vision is still blurred, do not take your next dose until you have spoken to a healthcare professional, and do not drive meanwhile.

Call NHS 111 for signs of faecal impaction (severe stomach pain, vomiting and being unable to open your bowels), difficulty emptying the bladder or starting to pass urine, signs of a severe urine infection such as fever, chills, burning, back pain or blood in the urine, or swelling of the ankles or legs. Call 999 for signs of anaphylaxis.

Suspected side effects can be reported through the Yellow Card scheme.

Solifenacin is not usually recommended in pregnancy because there is not enough information on safety, though continuing may sometimes be beneficial. It is permissible while breastfeeding if the baby is healthy, although other medicines may be preferred, and with long use it could build up in milk; contact a clinician about poor feeding, poor weight gain, constipation, reduced urination, irritability or colic in the baby. There is no evidence of reduced fertility.

The named interactions are itraconazole and ritonavir. Medicines that cause drowsiness, dry mouth or urinary difficulty may worsen those effects, and so can some herbal remedies. Turmeric may alter how the body processes solifenacin. Paracetamol and ibuprofen are safe to take with it.

Alcohol with solifenacin can make you very sleepy and may increase night-time toilet visits, so avoid it at first and when the dose changes. Do not drive, cycle or use tools or machinery if it makes you sleepy, blurs your vision or leaves you dizzy, clumsy or unable to concentrate.

You can eat normally, but cutting down on caffeine in tea, coffee and energy drinks may help the bladder. The NHS notes a possible link with confusion in older people with long-term use, though more research is needed, which is one reason for the regular reviews.