Liquorice root for stomach ulcers: evidence, blood pressure risks and NHS care

Natural liquorice, known as licorice in US English, is extracted from the root of a shrub and used medicinally as a capsule, tablet, liquid extract or topical gel, according to the MSD Manual. Glycyrrhizin is the active ingredient. The NHS uses liquorice root as its example when it explains what a herbal medicine is.

Some products are treated to contain far less glycyrrhizin, about one-tenth of the usual amount. These deglycyrrhizinated liquorice products are made for people who are particularly sensitive to the effects of glycyrrhizin.

People take liquorice to suppress coughs, soothe sore throats and relieve stomach upset, and it has been claimed to help treat stomach ulcers. The MSD Manual states that there is not enough evidence to determine whether liquorice is effective for stomach ulcers or for complications caused by hepatitis C or other liver diseases.

It does say that evidence indicates liquorice in combination with other herbs relieves symptoms of indigestion and irritable bowel syndrome, and that a liquorice lozenge helps symptoms of chronic cough. These are different questions from healing an ulcer, which has specific causes that need specific treatment.

When liquorice is consumed normally or at lower doses there are few side effects. At high doses, glycyrrhizin causes the kidneys to retain salt and water, possibly leading to high blood pressure, and to excrete potassium, possibly causing low blood potassium. Low potassium may lead to heart rhythm problems or muscle weakness.

Interactions follow from this. The MSD Manual says liquorice may decrease the effectiveness of blood pressure medicines, may interact with warfarin and make it less effective, may make some chemotherapy drugs less effective and may increase side effects of corticosteroids. People taking digoxin or diuretics that increase potassium loss should not take it.

The NHS says the main symptom of a stomach ulcer is tummy pain, usually in the upper tummy, that may feel like burning and is often worse at night. Indigestion, heartburn, bloating and feeling sick are other symptoms. The main causes are infection with Helicobacter pylori and regular use of anti-inflammatory painkillers such as ibuprofen, and ulcers are more common in smokers and older people.

A GP may arrange a breath test, a poo test or a blood test for H pylori, and you may be referred for a gastroscopy. Treatment depends on the cause: antibiotics for H pylori infection and medicines such as proton pump inhibitors to reduce stomach acid, usually for 1 week to 2 months, with a retest afterwards in some cases.

The NHS says to see a GP if you have indigestion that does not go away with treatment or tummy pain that keeps coming back. It advises an urgent GP appointment or NHS 111 for worsening pain, weight loss, loss of appetite or difficulty swallowing, and 999 or A&E if you are vomiting bright red blood or something like ground coffee, your poo is black, sticky and very smelly or contains blood, or you have severe tummy pain.

The NHS says an untreated stomach ulcer can cause serious problems that may be life-threatening, including bleeding, iron deficiency anaemia, a hole in the stomach that can cause peritonitis, and a higher risk of stomach cancer from an untreated H pylori infection. That is the main reason not to rely on a herbal remedy while symptoms continue.