← The ApothecaryGunneraceaerhizome, root, leaves, stemsFact-checked 24 October 2026

Significant riskHuman toxicity has not been studied. In Wistar rats, an aqueous leaf extract caused no deaths in an acute test, but 20% of rats died at 400 mg/kg in a subacute test and at 200 mg/kg in a chronic test, with mild splenic siderosis and kidney inflammation; reviewers consider it potentially toxic when taken for long periods. The labour mixture inembe, of which it is an ingredient, is often used as an abortifacient. Not for home use in pregnancy.In an emergency, call your local emergency number or poison centre.

River pumpkin

Gunnera perpensa

Also calledUgobho (Zulu) · Iphuzilomlambo (Xhosa) · Gobho (Swati)

A large-leaved wetland herb, the only African Gunnera, whose rhizome is one of southern Africa's best-known remedies to bring on labour and expel the placenta, often as part of mixed pregnancy decoctions such as isihlambezo. Rat-tissue studies confirm that extracts make the uterus contract, which is also the main reason for caution: there are no human trials, and its safety in pregnancy has never been established.

What it is used for

Childbirth and labour
Limited
Used by several southern African peoples to start or speed labour and ease childbirth, in women and in livestock. Aqueous extracts made isolated rat uterus contract and potentiated its response to oxytocin; there are no human studies of efficacy or safety.¹
Breast-milk supply
Limited
Zulu healers give a root decoction to stimulate milk. In lactating rats an oral aqueous rhizome extract increased milk production and mammary lobuloalveolar development without changing prolactin or other measured hormones. No human studies.^1,3
Intestinal worms
Limited
Used against intestinal worms in people and animals in Lesotho and South Africa. In village chickens an aqueous leaf extract reduced Heterakis gallinarum egg counts by 71–100%.¹
Wounds and cuts
Limited
Leaves are applied as hot poultices to wounds and boils in Lesotho, and a rhizome decoction is used as a dressing for wounds and psoriasis. Leaf extracts showed antibacterial activity in the laboratory, stronger than root extracts.¹
Pain (general)
Limited
Taken for general body pains and rheumatic pains. Rhizome extracts reduced pain responses in rodent tests and inhibited COX-2 in an enzyme assay.¹
Pregnancy and after birth
Traditional
Taken to expel the placenta and 'clear the womb' after birth, and as an ingredient of the antenatal tonic isihlambezo and the labour mixture inembe. A study of isihlambezo found pharmacological signs of both possible benefit and possible harm, and its effects on mother and baby have not been adequately studied.^1,2
Period pain
Traditional
In Lesotho a root decoction is used for menstrual pain and to regulate periods.¹

How it is prepared

decoction

Root or rhizome boiled in water and drunk, alone or mixed with other plants; this is the usual form. No reliable amount is recorded, and doses in mixed decoctions vary.

Childbirth and labour · Pregnancy and after birth · Breast-milk supply

poultice

Leaves heated and laid on wounds and boils, as recorded in Lesotho.

Wounds and cuts

food

Leaves cooked as a leafy vegetable in KwaZulu-Natal and Limpopo; roots and stalks are eaten and used in traditional beer in Eswatini.

Amounts are as recorded by the named source, not a recommendation.

Safety

Pregnancy: Contraindicated
Breastfeeding: Insufficient data
Children: No data.

Interactions with medicines

oxytocin and other uterotonic drugsMajorExtracts potentiated the response of isolated rat uterus to oxytocin; additive uterine stimulation is possible.

Interaction checker →

Do not use if

Pregnancy, except under medical supervision, because the rhizome stimulates uterine contraction and is also used as an abortifacient

In the healing traditions

African traditional medicine
Ugobho (Zulu)
Rhizome in isihlambezo, an antenatal decoction meant to ease childbirth and expel the placenta; root decoction to stimulate milk; leaves eaten as a vegetable (imifino).
Ethnobotanical records reviewed by Maroyi 2016
African traditional medicine
Iphuzilomlambo (Xhosa)
Stem decoction drunk for constipation; rhizome heavily traded in Eastern Cape muthi markets; leaves used in wound dressings.
Ethnobotanical records reviewed by Maroyi 2016
African traditional medicine
River pumpkin (Basotho use, Lesotho)
Root decoction for menstrual pain and irregular periods, for colic in pregnancy, to expel the placenta and as a vermifuge; leaves as hot poultices for wounds and boils, and burnt and smoked for headache.
Ethnobotanical records reviewed by Maroyi 2016

Active compounds

Z-venusol: isolated from the rhizome; induced sustained uterine contractility in rat tissue but not a direct contraction
benzoquinones (2-methyl-6-(3-methyl-2-butenyl)benzo-1,4-quinone and relatives): from leaves and stems; weak to moderate antibacterial activity
ellagic acid lactones: isolated from the roots
pyrogallol: from the rhizome; inhibited acetylcholinesterase and tumour-cell growth in vitro

History

The genus was named for the Norwegian bishop and botanist Johan Ernst Gunnerus, and G. perpensa was the first Gunnera described by Linnaeus, in 1767. In South Africa its rhizome is heavily traded: a 2016 review cites Eastern Cape traders selling a mean of about 116 kg a year each.

Sources

Reference, not prescription. Nothing here is medical advice. Herbs can interact with medicines and be dangerous in pregnancy; tell your doctor or pharmacist about anything you take.