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An essential guide to Lansoprazole side effects

Lansoprazole is a prescription drug and popular acid reflux treatment. While it’s safe for the majority of people to use, it’s important to know about potential side effects.

Keep reading to learn about short-term and long-term side effects of Lansoprazole and why it sometimes causes gastric issues.

Medically reviewed by Dr. Caroline Fontana Written by our editorial team Last reviewed 12-02-2024

Lansoprazole is a medicine that lowers stomach acid levels. It works to relieve and treat gastric conditions including:

  • heartburn, or acid reflux
  • gastro-oesophageal reflux disease (GORD)
  • indigestion
  • stomach ulcers
A visual representation of acid reflux

Lansoprazole is from a group of medicines called proton pump inhibitors (PPIs). These stop certain enzymes in the stomach lining from producing as much stomach acid.

Common side effects

Just like with any other medication, there is a chance that you’ll experience side effects while taking Lansoprazole. Not everyone gets them, but if you do they’ll likely be mild and go away once you stop taking treatment.

Common side effects tend to occur in more than 1 in 100 patients. These include:

  • diarrhoea
  • constipation
  • nausea
  • vomiting
  • stomach pain
  • flatulence (wind)
  • bloating
  • dry mouth
  • sore throat
  • a skin rash, or itching on the skin
  • tiredness
  • changes in liver function test values
  • benign polyps in the stomach (small, harmless masses of tissue)

Why does Lansoprazole cause gastric issues?

As seen above, many of the common side effects are gastric-related. This is because Lansoprazole (and all other PPIs) has an impact Trusted source National Center for Biotechnology Information (NCBI) Government Source Biomedical Research and Literature Go to source on the gut’s balance of good and bad bacteria.

A doctor and a diagram of the stomach and intestines

When your gut isn’t healthy, you can experience a wide range of stomach and digestive issues. PPIs can also cause diarrhoea through bacterial overgrowth in the small bowel. Due to this, these medications shouldn’t be overused.

Uncommon side effects

Before starting a new medication, you should also note the uncommon and rare side effects, even though it is unlikely that you’ll experience them.

Uncommon side effects tend to occur in less than 1 in 100 patients. These include:

  • joint or muscle pain
  • depression
  • fluid retention or swelling
  • changes in blood cell counts
  • an increased risk of hip, wrist, or spine fractures

Rare side effects

Rare side effects tend to occur in less than 1 in 1000 patients. These include:

  • fever
  • loss of appetite or a change in the way that things taste
  • drowsiness/confusion
  • visual disturbances such as blurred vision
  • skin reactions that feel like a burning or pricking sensation beneath the skin
  • swelling beneath the skin (angioedema)
  • kidney problems
  • pancreatitis
  • breast swelling in males
  • impotence
  • inflammation of the liver

Very rare side effects

Very rare side effects tend to occur in less than 1 in 10,000 patients. These include:

  • bowel inflammation
  • inflammation of the mouth
  • very severe skin reactions (blistering, reddening, severe skin inflammation)
  • a reduction in white blood cells, making you more susceptible to infection

Allergic reactions

Studies Trusted source National Center for Biotechnology Information (NCBI) Government Source Biomedical Research and Literature Go to source have shown that, in rare cases (1 in 1000), Lansoprazole can cause a severe allergic reaction called anaphylaxis. Anaphylaxis comes on suddenly and is potentially life-threatening.

Signs of a severe allergic reaction
  • swelling of the face, tongue, lips or throat
  • difficulty swallowing or breathing
  • a fever
  • hives (an allergic skin reaction)
  • a rapid fall in blood pressure

If you think you’re experiencing any of the above symptoms, stop taking Lansoprazole and seek emergency medical treatment.

Long-term side effects

If you’re planning on taking Lansoprazole for a prolonged period, it’s important to take note of the long-term side effects.

Magnesium deficiency

Taking Lansoprazole for more than 3 months can cause the magnesium levels in your blood to fall.

Signs of a magnesium deficiency include:

  • fatigue
  • involuntary muscle movements
  • disorientation
  • dizziness
  • an increased heart rate

If you experience any of these symptoms it’s important to tell your doctor promptly.

Low magnesium levels can also lead to reduced levels of calcium and/or potassium in the blood. Your doctor might suggest getting regular blood tests to monitor these levels throughout your treatment.

Bone health

Recent studies Trusted source National Center for Biotechnology Information (NCBI) Government Source Biomedical Research and Literature Go to source have found a link between proton pump inhibitors (PPIs) and a decrease in bone density. This in turn can increase your risk of bone fractures, especially if you are elderly.

One study about Lansoprazole in particular showed that, compared with other PPIs, it had a 44% lower risk of osteoporosis Trusted source National Center for Biotechnology Information (NCBI) Government Source Biomedical Research and Literature Go to source . This was proven to be the case across various age groups and genders.

Vitamin B12 deficiency

Taking Lansoprazole can also cause a vitamin B12 deficiency. This is because some PPIs can stop the production of folic acid, which is needed to help the body absorb and use vitamin B12.

To help regulate vitamin B12 levels you can supplement folic acid for the duration of your treatment.

Lansoprazole and anxiety

While there is no scientific evidence to suggest that PPIs like Lansoprazole can directly cause mental health issues, some patients have reported feeling anxious or depressed during treatment.

This could be caused by the relationship held between the gut and the brain. If your gut is out of balance it might have a negative impact on your brain function and mood.

Speak to your doctor if you have any concerns about your mental state being affected by Lansoprazole. They can offer advice and offer alternative medications.

Lansoprazole and low-sodium

A diminished level of sodium in the blood is referred to as hyponatraemia. While it has been reported that Lansoprazole can cause hyponatraemia, it is listed as a very rare side effect.

For other proton pump inhibitors, however, hyponatraemia is listed as a rare side effect.

If you’re concerned about any side effects you might be experiencing, it’s best to consult a doctor or healthcare professional.

Based on your symptoms, they can alter the dosage of your medication or suggest an alternative if you’re reacting badly.

Want to learn more about taking Lansoprazole?

Click here

Further reading

What not to take with Lansoprazole

Acid reflux treatments What not to take with Lansoprazole

Reviewed by Dr. Caroline Fontana
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