What is Liquorice?

Liquorice is the root of Glycyrrhiza glabra, a small legume shrub. In German it is called Süßholz, meaning "sweet wood". The dried root and its extracts go into sweets, teas, cough syrups and capsules.

European folk healers reached for it mainly for coughs, sore throats and upset stomachs. Long use in a tradition is not proof that a remedy works. It is also not proof that it is safe.

Honest verdict: human evidence for benefit is thin and comes from a few small trials. The harm side is better proven than the benefit side.

Glycyrrhizin, the sweet compound in the root, can raise blood pressure and drop potassium (a key body salt). That effect is well documented in people, and it is dose related.

How does Liquorice work?

The best-proven action of liquorice in people is on salt and water balance, and it is not a wanted one.

The gut turns glycyrrhizin into glycyrrhetinic acid. In people, this blocks a kidney enzyme (a helper protein) that normally switches off cortisol, a stress hormone. The body then holds sodium and water and loses potassium.

This is why blood pressure can rise, ankles can swell and muscles can weaken. The effect builds with daily use.

The soothing claims are less certain. In test tubes and animal work, liquorice compounds appear to calm inflammation and coat irritated tissue.

In lab tests, some compounds slow Helicobacter pylori, a stomach bug linked to ulcers. Whether that happens inside a person's stomach is not established.

DGL stands for deglycyrrhizinated liquorice, which has most glycyrrhizin stripped out. The idea is to keep the soothing feel without the blood pressure risk. Human proof that DGL helps ulcers or indigestion is limited and mostly old.

What forms does Liquorice come in?

The key question with any form is how much glycyrrhizin it carries, and that varies hugely.

Dried root pieces and root powder are brewed as tea or chewed.

Teabags and cut-root blends appear in many cough and stomach teas, often mixed with other herbs.

Liquid extracts and tinctures are concentrated. Strength differs from maker to maker.

Capsules and tablets often state a glycyrrhizin amount on the label. That number is worth reading.

DGL chewable tablets have most of the glycyrrhizin removed. They are sold for stomach complaints.

Liquorice sweets and salty liquorice count too. So do some pastis-style drinks, herbal cough syrups and chewing tobaccos. People often forget these add up.

Gels and creams with glabridin are sold for skin tone. Human evidence for that use is weak.

Where it comes from:

Liquorice has one of the longest records of any European herb. Greek and Roman writers described the sweet root, and it later filled monastery gardens.

In German-speaking lands it was known as Süßholz. Bamberg in Bavaria grew it on a large scale for centuries.

Folk use centred on dry coughs, hoarseness, sore throats and sour stomachs. It was boiled into black sticks, syrups and lozenges.

Apothecaries also used it to mask the taste of bitter medicines. That habit carried into modern pharmacy.

From the 1900s it became a sweet as much as a medicine, especially in the Netherlands and the Nordic countries. Its salt and water effect was only described by doctors in the mid-20th century, after cases of swelling and high blood pressure.

What does Liquorice help with?

• Indigestion (ongoing discomfort in the upper stomach): Folk use treated liquorice as a stomach soother. One small randomised trial of a liquorice extract reported fewer symptoms than placebo over 30 days. The trial was small and industry-linked, so this is a hint, not a settled answer.
• Sore throat and dry cough: European tradition used liquorice syrups and lozenges for hoarseness. A randomised trial found a liquorice gargle before surgery cut sore throat afterwards. For everyday colds, the evidence is mostly the sweet, coating feel rather than proof of healing.
• Mouth ulcers (small sores inside the mouth): Liquorice patches and pastes have been tried for these sores. A few small studies report less pain and faster healing. The studies are small and not well replicated.
• Heartburn and acid reflux: DGL chewables are widely sold for reflux. Trial support is thin and dated. Any relief is likely short-lived and does not treat the cause.
• Stomach and duodenal ulcers (DGL form): DGL was studied for ulcers in the 1970s and 1980s, before modern acid-blocking drugs. Those studies are old and hard to judge today. Proven drug treatments now exist, so ulcers need a doctor, not self-treatment.
• Tiredness and low blood pressure (traditional claim only): Liquorice does raise blood pressure, which is why it was once given for faintness. It is sometimes marketed for "adrenal fatigue", which is not a recognised medical diagnosis. Using liquorice this way risks the very harms listed on this page.

Which foods are rich in Liquorice?

1. Liquorice sweets and black liquorice sticks
2. Salty liquorice (salmiak)
3. Liquorice root tea
4. Herbal cough and stomach tea blends
5. Some pastis-style and anise liqueurs
6. Some chewing tobacco and snuff
7. Some herbal cough syrups and lozenges

Practical Tips:

Food sources matter here more than with most herbs. A daily bag of liquorice sweets can carry more glycyrrhizin than a supplement.

In the EU, sweets above a set level must say "contains liquorice" on the pack. Anise-flavoured foods are not the same thing and often contain no liquorice at all.

What are the side effects of Liquorice?

• Raised blood pressure
• Low potassium (hypokalaemia), a salt imbalance in the blood
• Fluid retention, with puffy ankles, hands or face
• Headache
• Muscle weakness, cramps or twitching
• Irregular or racing heartbeat
• Severe tiredness
• Muscle breakdown (rhabdomyolysis) in heavy use
• Temporary paralysis in rare, severe cases
• Changes in periods, and lower testosterone reported in some men
• Upset stomach

Good to know:

Mild effects such as puffiness and headache are common with daily use. They can start within one to two weeks.

Serious effects are less common but real. Hospital cases of very low potassium, heart rhythm problems and muscle breakdown are well documented, including deaths after heavy liquorice sweet intake.

Some people are far more sensitive than others at the same amount. Risk rises with age, heart disease, kidney disease and certain medicines.

How much Liquorice should you take?

• Recommended daily: What follows is what labels and food authorities state. It is not advice for you. European food safety advice has long flagged 100 mg of glycyrrhizin a day as an upper limit for regular use by healthy adults. Many people pass that with sweets or strong tea alone. Labels on dried root products commonly list about 1.5 to 4 g of root per day. Extract strength varies widely between brands. If you have heart, kidney, liver or blood pressure problems, get personal advice before using any amount. The same goes for anyone on the medicines listed below.
• Best time of day: Timing makes little difference to safety. Traditional stomach use put DGL chewables shortly before meals. Teas were sipped through the day. That habit makes it easy to take far more than you planned.
• With or without food: Either is fine. DGL chewables were traditionally used just before food. Taking it with food may ease queasiness. Food does not reduce the blood pressure risk.
• Time to effect: A soothing feel in the throat can be immediate, but that is taste and coating, not healing. Indigestion trials ran for two to four weeks. Any benefit, if it comes, is gradual. It may also do nothing for you.
• How long to take it: Short term only. European herbal guidance caps traditional use of liquorice root at about four weeks. The salt and water effect builds the longer you take it. Harm has been reported in people who ate liquorice sweets daily for months. If your symptoms last beyond a few weeks, see a doctor instead of carrying on.