Health Care Professional Information

Scientific Name
Carica papaya
Common Name

Pawpaw, papaw

Clinical Summary

Papaya tree is commonly found in tropical areas around the world. The fruits are consumed as food and as medicine; dried and powdered stem and leaves are used to prepare medicinal teas against infections and to improve digestion. Papaya leaves and their extracts are also marketed as dietary supplements to enhance the immune system, to improve platelet function, and to prevent chemotherapy-related adverse effects.
Papaya leaves exhibit anti-tumor, immunomodulatory (1), and antioxidant(9) effects in vitro.
The leaf extracts contain antibacterial compounds that inhibit the growth of a wide variety of Gram-positive and Gram-negative bacteria (4).
In mice, a powdered suspension of papaya leaves increased thrombocyte count (2) and a water extract reduced alcohol-induced stomach damage (5). Hypoglycemic effects were also reported with use of papaya leaf extract in streptozotocin-induced diabetic rats (10).

According to a case report, a water extract of papaya leaves was shown to increase the platelet count of a patient with Dengue fever (3).

Papaya leaf extract showed low toxicity (6) in an animal model, but it has not been studied in humans. An international patent has been filed for its use in increasing low platelet counts (7).
Papaya leaf extracts should not be used as a treatment for cancer or for low platelet count until more is known about its efficacy and adverse effects in humans.

Purported Uses
  • Antimicrobial
  • Improve platelet count

Carpaine, malic acid, quinic acid, manghaslin and clitorin, minor quantities of various malic acid derivatives, nicotiflorin, and rutin.(6)
Phenolic compounds: Dimethoxycoumarin, protocatechuic acid, p-coumaric acid, caffeic acid, chlorogenic acid, kaempferol and quercetin. (8)

Mechanism of Action

Papaya leaf extract modulates the immune system by enhancing the production of Th1 type cytokines, such as interleukin (IL-12), interferon (IFN-gamma) and tumor necrosis factor (TNF-alpha). Fractions with molecular weight less of than 1000 are most active in inhibiting tumor cell growth (1). Papaya leaf extract also has antioxidant effects (5) and contains antibacterial compounds, but the mechanism of action remains unclear.

Adverse Reactions
  • Papaya leaf extract has not been tested in humans. Animal studies suggest low toxicity (6).
Herb Lab Interactions
  • According to a case report, a water extract of papaya leaf increased platelet count (3).
Dosage (Inside MSKCC Only)
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  1. Otsuki N, Dang NH, Kumagai E, et al. Aqueous extract of Carica papaya leaves exhibits anti-tumor activity and immunomodulatory effects. J Ethnopharmacol. Feb 17 2010;127(3):760-767.
  2. Sathasivam K, Ramanathan S, Mansor SM, et al. Thrombocyte counts in mice after the administration of papaya leaf suspension. Wiener klinische Wochenschrift. Oct 2009;121 Suppl 3:19-22.
  3. Ahmad N, Fazal H, Ayaz M, et al. Dengue fever treatment with Carica papaya leaves extracts. Asian Pacific Journal of Tropical Biomedicine. 2011:330-333.
  4. Rahman S, Imran M, Muhammad N, et al. Antibacetial screening of leaves and stem of Carica papaya. Journal of Medicinal Plants Research. 2011; 5(20):5167-5171.
  5. Indran M, Mahmood AA, Kuppusamy UR. Protective effect of Carica papaya L leaf extract against alcohol induced acute gastric damage and blood oxidative stress in rats. West Indian Med J. Sep 2008;57(4):323-326.
  6. Afzan A, Abdullah NR, Halim SZ, et al. Repeated Dose 28-Days Oral Toxicity Study of Carica papaya L. Leaf Extract in Sprague Dawley Rats. Molecules. 2012;17(4):4326-4342.
  7. Alva J. Increasing Low Platelets Instantly. International Publication Number WO 2010041263. World Intellectual Property Organization. 2010.
  8. Antonella DA, D’Arcangelob G, Tagliatestab P. Gas chromatography–mass spectrometry analysis of phenolic compounds from Carica papaya L. Journal of Food Composition and Analysis. 2007;20:584-590.
  9. Okoko T, Ere D. Reduction of hydrogen peroxide-induced erythrocyte damage by Carica papaya leaf extract.Asian Pac J Trop Biomed.2012 Jun;2(6):449-53.
  10. Juárez-Rojop IE, Díaz-Zagoya JC, Ble-Castillo JL, et al. Hypoglycemic effect of Carica papaya leaves in streptozotocin-induced diabetic rats.BMC Complement Altern Med. 2012 Nov 28;12:236.

Consumer Information

How It Works

Bottom Line: Papaya leaf extract has not been shown to treat or prevent cancer.

Papaya tree is common to many tropical regions of the world. Papaya leaves and their extracts are sold as dietary supplements to improve immune system, platelet counts, and to prevent side effects of chemotherapy. Laboratory and animal studies show that papaya leaf extracts can stop growth of a variety of bacteria, improve platelet count, and reduce stomach damage caused by alcohol. Human studies have not been conducted.


Purported Uses
  • Antimicrobial
    Lab studies show that papaya leaf extracts can stop the growth of a variety of bacteria.
  • Improve platelet count
    A papaya leaf extract increased platelet count in a patient with Dengue fever. More studies are needed.
Side Effects
  • Papaya leaf extract has not been tested in humans. It showed low toxicity in animal studies.
Special Point
  • Papaya leaf extracts should not be used as a treatment for cancer or for low platelet count until more is known about its efficacy and adverse effects in humans.  
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