Lansoprazole: uses, side effects and cautions

Lansoprazole lowers stomach acid. The NHS lists indigestion, heartburn and acid reflux, gastro-oesophageal reflux disease, the prevention and treatment of stomach ulcers, and Zollinger-Ellison syndrome, a rare condition in which a tumour drives acid production.

It is a proton pump inhibitor, a group that works by blocking the enzymes in the stomach lining that make acid. Unlike antacids, which neutralise acid after the event, it reduces the amount produced in the first place.

The brand name given by the NHS is Zoton FasTabs, the melt-in-the-mouth version. Generic lansoprazole capsules are widely prescribed.

Most people take lansoprazole once a day, first thing in the morning, ideally at least 30 minutes before eating. The NHS gives usual daily amounts of 15 mg to 30 mg for indigestion, reflux and ulcers, with considerably higher amounts used for Zollinger-Ellison syndrome and lower amounts for children, older people and people with liver problems. Your own dose is set by your prescriber.

Capsules should be swallowed whole with water or juice. If swallowing is hard, a capsule can be opened and the granules mixed with water, juice, yoghurt or apple puree, but the granules must not be crushed or chewed. The orodispersible tablet is simply placed on the tongue to melt.

• Leave about two hours between lansoprazole and an antacid, either side, because antacids reduce how much is absorbed.

• Length of treatment ranges from a few weeks to many years. Some people only take it when symptoms return.

• If you take it once daily and are less than 12 hours late, take it; after 12 hours, skip it. For twice-daily doses the cut-off is 4 hours.

• Never take two doses together to catch up.

The NHS says most adults and children can take lansoprazole, but you should tell the prescriber about a past allergic reaction to it or other medicines, liver problems and low vitamin B12. If you are pregnant, trying for a baby or breastfeeding, mention it too.

Anyone booked for an endoscopy should ask whether to stop lansoprazole several weeks ahead, because the medicine can conceal the very changes the test is meant to find.

Some symptoms should not be self-treated with an acid reducer. The NHS lists unexplained weight loss, repeated vomiting or vomiting blood that looks like coffee grounds, black tarry stools, unusual weakness or paleness, chest or stomach pain, severe or persistent diarrhoea, and difficulty swallowing as reasons to see a doctor.

Common effects, affecting more than 1 in 100 people, include headache, nausea or vomiting, diarrhoea, stomach pain, constipation, wind, an itchy mild rash, dizziness or tiredness, and a dry mouth or throat. Eating smaller plainer meals, drinking water and resting usually helps while they settle. Severe sickness or diarrhoea can make the combined contraceptive pill less reliable.

Less than 1 in 1,000 people have a serious reaction. The NHS advises contacting a doctor or NHS 111 for worsening stomach pain with yellow skin or eyes and dark urine, for joint pain with a red rash on sun-exposed skin, or for severe and persistent diarrhoea.

• Call 999 if your lips, mouth, throat or tongue swell, or if you struggle to breathe, as these can signal anaphylaxis.

• After more than 3 months, low magnesium can cause tiredness, confusion, dizziness, muscle twitches and an irregular heartbeat; call NHS 111 if these appear.

• After a year or more, there is a higher chance of fractures, gut infections and vitamin B12 deficiency.

Lansoprazole can be taken during pregnancy, but doctors usually prefer omeprazole because far more safety information exists for it. The same applies to breastfeeding, where omeprazole or pantoprazole are usually favoured. Small amounts pass into breast milk, and babies should be watched for poor feeding, constipation, diarrhoea, vomiting, irritability or unsettled sleep. The NHS says there is no evidence that lansoprazole affects fertility.

The NHS names these medicines to discuss before starting: digoxin, the antifungals itraconazole and posaconazole, methotrexate, HIV medicines, rifampicin, warfarin, fluvoxamine and tacrolimus. Antacids reduce its effect, so they are spaced out. St John's wort may stop lansoprazole working properly and should be avoided.

People on lansoprazole for more than a year are offered regular health checks. The NHS also notes some evidence that medicines reducing stomach acid might carry a very small increase in stomach cancer risk after three or more years, though more research is needed and a link has not been proven.

Alcohol is allowed, but heavy drinking raises acid and can bring the symptoms back. If lansoprazole makes you dizzy, sleepy or affects your sight, do not drive or cycle.

Alongside the medicine, the NHS suggests keeping to a healthy weight, cutting back on rich, spicy, fatty and acidic food and on caffeine, stopping smoking, leaving three hours between eating and bed, sitting upright to eat and raising the head and shoulders in bed.

Omeprazole, esomeprazole and pantoprazole belong to the same class and are interchangeable in many situations; each has its own guide here. Antacids and alginates such as Gaviscon act differently and may be used for occasional symptoms.

Any decision to switch, reduce or stop lansoprazole belongs with your prescriber or pharmacist. Suspected side effects can be reported through the Yellow Card scheme.