Dandelion root

What dandelion root is

The common dandelion (Taraxacum officinale) belongs to the daisy family. The parts used medicinally are the root, often together with the herb, and the leaves. The root contains bitter substances from the group of sesquiterpene lactones, such as a glucoside of taraxinic acid, and, depending on the time of harvest, 2 percent (spring) to 40 percent (autumn) inulin, a fiber that is also sold as a prebiotic.

In German folk medicine, dandelion has been documented since the 16th century; preparations of dandelion root and herb have been on the market since 1976, as coated tablets with dry extract, as drops and as pressed juice. In the BK-Score, it has 2 out of 10 points for human evidence and 8 for track record of use. This is the typical case of a plant that has long been used but barely studied.

How it works

The HMPC, the EMA’s Committee on Herbal Medicinal Products, explains the digestive effect by the bitter substances: via the bitter receptors, they are said to reflexively stimulate saliva and gastric juice and promote bile flow. In animal experiments, bile flow in rats rose by up to 40 percent after a decoction of dandelion leaves.

The HMPC attributes the diuretic effect to the high potassium content and certain flavonoids, but notes that no study confirms this assumption.

What the studies show

Leaf extract and urine output: Clare 2009

In this pilot study, 17 volunteers took 8 ml of a fresh alcoholic extract of dandelion leaves three times in one day; the comparison was with their own values from the two preceding days. In the 5 hours after the first dose, the frequency of urination increased, and after the second dose the ratio of urine output to fluid intake. The third dose changed nothing further. The leaf was studied, not the root, and there was no placebo group.

Root powder and urine output: Gavin 2026

In an open-label crossover study, 14 physically active young adults drank 1 liter of water on two occasions, once with four capsules of a commercially available root powder, about 2.1 g in total. Over 4 hours, they excreted a mean of 1,268 g of urine with dandelion and 1,164 g without; the difference of 105 g was not significant. The authors therefore see no confirmation of the diuretic effect, but consider other doses, time frames and preparations worth testing.

The EU’s assessment: HMPC 2009 and 2019

In 2009, the HMPC reviewed the literature and found no clinical studies with preparations of dandelion root and herb. Recognition as a medicine with established efficacy was therefore not possible, but recognition as a traditional herbal medicine was. The 2019 review added 39 new papers, but no clinical study and no new safety concerns. For a new review, the HMPC requested scientific data from March to June 2026.

Where the data stop

• Efficacy for digestive complaints. There is no clinical study on this; recognition rests solely on long-standing use.
• Diuresis with the root. The only study with root powder found no significant effect; the positive finding comes from the leaf and was obtained without a placebo group.
• Relieving the liver. For liver disease, the EU monograph even lists a contraindication; there are no data on relieving or detoxifying the liver.
• Long-term safety. Studies on genetic damage, reproduction and cancer risk are lacking.

Status, approval and legal

An HMPC EU monograph on dandelion root and herb has existed since 2009. It allows registration as a traditional herbal medicine for mild digestive complaints such as a feeling of fullness, bloating and sluggish digestion, for temporary loss of appetite and to increase the amount of urine in order to flush the urinary tract in mild urinary complaints. The basis is solely long-standing use. Use in children under 12 is not intended due to a lack of data.

Dandelion root is also offered as a tea and in dietary supplements. Dandelion is not on the EU list of authorized health claims.

Safety

The monograph lists as contraindications an allergy to plants of the daisy family, obstruction or inflammation of the bile ducts, liver disease, gallstones, an active stomach ulcer and other diseases of the bile ducts. In impaired kidney function, diabetes or heart failure, dandelion should be avoided because of a possible potassium excess. The side effects described are stomach pain, hyperacidity and allergic reactions; their frequency is unknown.

There are no data for pregnancy and breastfeeding, nor studies on genetic damage, reproduction and cancer risk. In the BK-Score, safety stands at 3 out of 10 points; this axis measures how well safety has been studied, not how safe the substance is. This text is information and does not replace medical advice.

Sources

• HMPC 2009 – Community herbal monograph on Taraxacum officinale Weber ex Wigg., radix cum herba (EMA/HMPC/212895/2008 Corr. 1)
• HMPC 2009 – Assessment report on Taraxacum officinale Weber ex Wigg., radix cum herba (EMA/HMPC/212897/2008)
• HMPC 2019 – Addendum to Assessment report, periodic review 2009 to 2019 (EMA/HMPC/514844/2019)
• EMA – Taraxaci radix cum herba, overview of the herbal medicine and ongoing review 2026
• Clare BA et al., J Altern Complement Med 2009 – pilot study, 17 volunteers, leaf extract and urine output
• Gavin J et al., Int J Sport Nutr Exerc Metab 2026 – open-label crossover study, 14 young adults, root powder and urine output
• Regulation (EU) No 432/2012 – list of permitted health claims made on foods