Last update: Dec. 30, 2020

Hashish, Hash

Very High Risk for breastfeeding

Very unsafe. Contraindicated.
Use of an alternative or cessation of breastfeeding.

Hemp (Cannabis sativa), is a plant rich in cannabinoids, the main one being Δ9-TetraHydroCannabinol (THC) which has psychotropic properties. Other cannabinoids, which lack psychoactive effects are cannabidiol (CBD), cannabigerol, cannabinol and Δ8-tetrahydrocannabinol (ElSohly 2017).
It also contains numerous flavonoids, phytosterols, vitamins, fatty acids, amino acids, proteins, enzymes, sugars, alkaloids and essential oil, among others.
Cannabis preparations can be taken orally, inhaled by vaporization, topically or in rectal suppositories.

Cannabis oil is a resinous substance extracted from the Cannabis plant (sativa or indica). It contains the plant’s main cannabinoids, including THC and CBD. Depending on the method of extraction or manufacture of cannabis oil, it may contain more or less THC.
There are several CBD-based medicines that contain varying amounts of THC, for the treatment of vomiting during anti-cancer treatments and to treat pain, spasticity or epilepsy in certain diseases.

Delta-9-TetraHydroCanabinol (THC) is fat soluble, accumulates in fatty tissue and reaches up to 8.4 times the plasma concentration in breastmilk (Pérez 1982).
THC is excreted in breastmilk in amounts that could be significant (RD up to 8.7%) as it is a psychotropic drug; CBD is excreted in very small amounts (Bertrand 2018, Baker 2018, Marchei 2011).
THC is detected in breastmilk up to 3 to 6 weeks after its last use (Wymore 2018).
THC has been found in much higher quantities than expected in faeces of infants whose mothers smoked marijuana, suggesting subsequent absorption and metabolization: marijuana is excreted mainly by faeces (Pérez 1982).

THC is highly lipophilic, so it accumulates in fatty tissues, such as the brain (Ryan 2018). Cannabinoids, mainly THC, can disrupt normal axonal growth in developing brains (Tortoriello 2014).
The body's endocannabinoid system has a key role in brain development during pregnancy, breastfeeding and adolescence and is affected by the external input of THC, so exposure to THC during pregnancy and breastfeeding is of concern, since it can cause epigenetic changes in brain development (Henschke 2019, Sachs 2013, Campolongo 2009, Fernández 2004).

There are few studies about the effects of maternal cannabis use on breastfed infants and it is difficult to separate them from use during pregnancy.
A link has been found between exposure during the prenatal period and breastfeeding and neurodevelopmental delay, cognitive deficit, behavioural alterations (including criminal behaviour), drug use and attention deficit disorder in childhood and adolescence (Smith 2016, Tortoriello 2014, Sharma 2012, Goldschmidt 2012 and 2008, Jaques 2005, Fried 2001 and 1995, Day 2011, 2006 and 1994).
Two studies found no delay in short- to medium-term growth or psychomotor development in infants of mothers who smoke marijuana (Ilett 2012, Tennes 1985).
One study found motor delay at one year of age in infants of mothers who smoked marijuana; the delay was dose-dependent: the delay is greater the more they smoked and is also greater if they did so during the first month (Moretti 2000, Astley 1990).
Maternal cannabis use during pregnancy is related to lower birth weight and head circumference (El Marroun 2009, Fergusson 2002, Fried 1999).
Paternal marijuana use was associated with an increased risk of sudden infant death (Klonoff 2001).

Cannabis use is associated with increased cortisol levels and decreased prolactin levels (Ranganathan 2009, D'Souza 2008, Mendelson 1985); other authors have not found hormonal alterations (Block 1991).
Cannabis use is associated with a shorter duration of breastfeeding (Crume 2018. Ko 2018), increased tobacco use and postpartum depression (Ko 2018).
The alteration of judgment and behaviour and the greater frequency of mental disorders (Volkow 2014, Moore 2007) which cannabis use produces can interfere with the mother’s capacity for adequate care (Colorado DPHE 2017, Lawrence 2016 p604, Jansson 2015, ABM 2015, Jaques 2014, D'Souza 2008).

Various medical associations, experts and expert consensus consider the use of cannabis, both recreationally and medicinally, to be contraindicated during pregnancy and breastfeeding (Adashi 2019, van den Elsen 2019, Thompson 2019, Hale 2019, Ryan 2018, Jansson 2018, Krening 2018, Metz 2018 and 2015, Obs-Gyn Committee 2017, Jansson 2015, Briggs 2015, Warner 2014, Rowe 2013, Garry 2009, Schaefer 2007).
Until more information is published regarding breastfeeding and cannabis products for medicinal use, safer known pharmacological alternatives are preferable.

Other authors, given the risks of formula feeding and the lack of accurate data on the effects of cannabis on breastfeeding, choose to advise mothers not to give up its use, to continue breastfeeding and minimize cannabis use, avoid using it in the same room and monitor the possible effects on infants (Anderson 2017, ABM 2015, Djulus 2005).

The proportion of THC in the various products derived from marijuana has been progressively increasing over the last few years (Metz 2015).

Mothers who breastfeed should be warned of the possible negative effects of THC on the brain and neurobehavioral development of their babies in the short and long term, and they should be advised to eliminate the use of marijuana in any form during breastfeeding.

Sharing a bed with the baby is not recommended if this drug is being used due to an increased risk of suffocation or sudden infant death (UNICEF 2018, 2017, 2014 and 2013, Landa 2012, ABM 2008, UNICEF 2006).

See below the information of these related products:

Suggestions made at e-lactancia are done by APILAM´s pediatricians and pharmacists, and are based on updated scientific publications.
It is not intended to replace the relationship you have with your doctor but to compound it.

Jose Maria Paricio, Founder & President of APILAM/e-Lactancia

Your contribution is essential for this service to continue to exist. We need the generosity of people like you who believe in the benefits of breastfeeding.

Thank you for helping to protect and promote breastfeeding.

José María Paricio, founder of e-lactancia.

Other names

Hashish, Hash is also known as Cannabis. Here it is a list of alternative known names::

Hashish, Hash in other languages or writings:


Hashish, Hash belongs to this group or family:


Main tradenames from several countries containing Hashish, Hash in its composition:


Variable Value Unit
Oral Bioavail. THC: 10 - 35 %
Molecular weight THC: 314 daltons
Protein Binding THC: 99 %
VD THC: 4 - 19 l/Kg
Tmax THC: 0,1 - 4; CBD: 1,6 - 2,8 hours
T1/2 THC: 28 - 56; CBD: 1,4 - 1,8 hours
M/P ratio THC: 8 -


  1. Adashi EY. Brief Commentary: Marijuana Use During Gestation and Lactation-Harmful Until Proved Safe. Ann Intern Med. 2019 Jan 15;170(2):122. Abstract
  2. Henschke P. Cannabis: An ancient friend or foe? What works and doesn't work. Semin Fetal Neonatal Med. 2019 Apr;24(2):149-154. Abstract
  3. van den Elsen GAH, In 't Hout FEM, de Vries M, Olde Rikkert MGM, Kramers C, Verkes RJ. [Medicinal cannabis]. Ned Tijdschr Geneeskd. 2019 May 3;163. pii: D3629. Dutch. Abstract
  4. Thompson R, DeJong K, Lo J. Marijuana Use in Pregnancy: A Review. Obstet Gynecol Surv. 2019 Jul;74(7):415-428. Abstract
  5. UNICEF UK. Caring for your baby at night. A guide for parents. 2018 Full text (link to original source) Full text (in our servers)
  6. Wymore E, Bunik M, Levek C, Wang G, Metz T, Bourne D, Sempio C, Klawitter J. Duration of marijuana excretion in human breast milk. Breastfeed Med. 2018;13 (S-2):S-40. Abstract 92. Full text (link to original source) Full text (in our servers)
  7. Krening C, Hanson K. Marijuana-Perinatal and Legal Issues With Use During Pregnancy. J Perinat Neonatal Nurs. 2018 Jan/Mar;32(1):43-52. Abstract
  8. Crume TL, Juhl AL, Brooks-Russell A, Hall KE, Wymore E, Borgelt LM. Cannabis Use During the Perinatal Period in a State With Legalized Recreational and Medical Marijuana: The Association Between Maternal Characteristics, Breastfeeding Patterns, and Neonatal Outcomes. J Pediatr. 2018 Jun;197:90-96. Abstract
  9. Ko JY, Tong VT, Bombard JM, Hayes DK, Davy J, Perham-Hester KA. Marijuana use during and after pregnancy and association of prenatal use on birth outcomes: A population-based study. Drug Alcohol Depend. 2018 Jun 1;187:72-78. Abstract
  10. Baker T, Datta P, Rewers-Felkins K, Thompson H, Kallem RR, Hale TW. Transfer of Inhaled Cannabis Into Human Breast Milk. Obstet Gynecol. 2018 May;131(5):783-788. Abstract
  11. Jansson LM, Jordan CJ, Velez ML. Perinatal Marijuana Use and the Developing Child. JAMA. 2018 Aug 14;320(6):545-546. Abstract
  12. Bertrand KA, Hanan NJ, Honerkamp-Smith G, Best BM, Chambers CD. Marijuana Use by Breastfeeding Mothers and Cannabinoid Concentrations in Breast Milk. Pediatrics. 2018 Sep;142(3). pii: e20181076. Abstract
  13. Ryan SA, Ammerman SD, O'Connor ME; COMMITTEE ON SUBSTANCE USE AND PREVENTION.; SECTION ON BREASTFEEDING.. Marijuana Use During Pregnancy and Breastfeeding: Implications for Neonatal and Childhood Outcomes. Pediatrics. 2018 Sep;142(3). pii: e20181889. Abstract
  14. Ryan SA. A Modern Conundrum for the Pediatrician: The Safety of Breast Milk and the Cannabis-Using Mother. Pediatrics. 2018 Sep;142(3). pii: e20181921. Abstract
  15. Metz TD, Borgelt LM. Marijuana Use in Pregnancy and While Breastfeeding. Obstet Gynecol. 2018 Nov;132(5):1198-1210. Abstract
  16. Ball H, Blair PS. (For UNICEF UK). Caring for your baby at night. Health professional´s guide. 2017 Full text (link to original source) Full text (in our servers)
  17. Colorado Department of Public Health and Environment. Marijuana pregnancy and breast-feeding guidance for Colorado health care providers. pacific/sites/default/files/MJ_RMEP_ Marijuana pregnancy and breast-feeding guidance for Colorado health care providers. Published 2017. Accessed January 2, 2018. Pregnancy-Breastfeeding- Clinical-Guidelines.pdf. 2017 Full text (link to original source) Full text (in our servers)
  18. ElSohly MA, Radwan MM, Gul W, Chandra S, Galal A. Phytochemistry of Cannabis sativa L. Prog Chem Org Nat Prod. 2017;103:1-36. Abstract
  19. Committee on Obstetric Practice.. Committee Opinion No. 722: Marijuana Use During Pregnancy and Lactation. Obstet Gynecol. 2017 Oct;130(4):e205-e209. Abstract
  20. Anderson PO. Cannabis and Breastfeeding. Breastfeed Med. 2017 Dec;12(10):580-581. Abstract
  21. Lawrence RA, Lawrence RM. Breastfeeding. A guide for the medical profession. Eighth Edition. Philadelphia: Elsevier; 2016
  22. Smith AM, Mioduszewski O, Hatchard T, Byron-Alhassan A, Fall C, Fried PA. Prenatal marijuana exposure impacts executive functioning into young adulthood: An fMRI study. Neurotoxicol Teratol. 2016 Nov - Dec;58:53-59. Abstract
  23. ABM. Reece-Stremtan S, Marinelli KA. ABM Clinical Protocol #21: Guidelines for Breastfeeding and Substance Use or Substance Use Disorder, Revised 2015. Breastfeed Med. 2015 Abstract Full text (link to original source) Full text (in our servers)
  24. ABM Protocolo clínico de la ABM n.º 21: Pautas para la lactancia y el consumo de sustancias o trastorno por consumo de sustancias, revisado en 2015. Breastfeed Med. 2015 Full text (link to original source) Full text (in our servers)
  25. Briggs GG, Freeman RK, Towers CV, Forinash AB. Drugs in Pregnancy and Lactation: A Reference Guide to Fetal and Neonatal Risk. Wolters Kluwer Health. Tenth edition (acces on line) 2015
  26. Metz TD, Stickrath EH. Marijuana use in pregnancy and lactation: a review of the evidence. Am J Obstet Gynecol. 2015 Dec;213(6):761-78. Abstract
  27. Jansson LM, Bunik M, Bogen DL. Lactation and the Marijuana-Using Mother. Breastfeed Med. 2015 Jul-Aug;10(6):342-3. Abstract
  28. Jaques SC, Kingsbury A, Henshcke P, Chomchai C, Clews S, Falconer J, Abdel-Latif ME, Feller JM, Oei JL. Cannabis, the pregnant woman and her child: weeding out the myths. J Perinatol. 2014 Abstract
  29. UNICEF UK. Statement on co-sleeping following publication of new NICE postnatal guidance. Infosheet. 2014 Full text (link to original source) Full text (in our servers)
  30. Tortoriello G, Morris CV, Alpar A, Fuzik J, Shirran SL, Calvigioni D, Keimpema E, Botting CH, Reinecke K, Herdegen T, Courtney M, Hurd YL, Harkany T. Miswiring the brain: Δ9-tetrahydrocannabinol disrupts cortical development by inducing an SCG10/stathmin-2 degradation pathway. EMBO J. 2014 Apr 1;33(7):668-85. Abstract
  31. Volkow ND, Baler RD, Compton WM, Weiss SR. Adverse health effects of marijuana use. N Engl J Med. 2014 Jun 5;370(23):2219-27. Abstract
  32. Warner TD, Roussos-Ross D, Behnke M. It's not your mother's marijuana: effects on maternal-fetal health and the developing child. Clin Perinatol. 2014 Dec;41(4):877-94. Abstract
  33. Sachs HC; Committee On Drugs. The transfer of drugs and therapeutics into human breast milk: an update on selected topics. Pediatrics. 2013 Sep;132(3):e796-809. Abstract Full text (link to original source) Full text (in our servers)
  34. Rowe H, Baker T, Hale TW. Maternal medication, drug use, and breastfeeding. Pediatr Clin North Am. 2013 Feb;60(1):275-94. Abstract
  35. UNICEF UK Baby Friendly Initiative statement on Bed-sharing when parents do not smoke: is there a risk of SIDS? An individual level analysis of five major case-control studies. 2013 Full text (link to original source) Full text (in our servers)
  36. D'Apolito K. Breastfeeding and substance abuse. Clin Obstet Gynecol. 2013 Mar;56(1):202-11. Abstract
  37. L.Landa Rivera, M.Díaz-Gómez, A.Gómez Papi, J.M.Paricio Talayero, C.Pallás Alonso, M.T.Hernández Aguilar, J.Aguayo Maldonado, J.M.Arena Ansotegui, S.Ares Segura, A.Jiménez Moya, J.J.Lasarte Velillas, J.Martín Calama, M.D.Romero Escós. El colecho favorece la práctica de la lactancia materna y no aumenta el riesgo de muerte súbita del lactante. Dormir con los padres. Rev Pediatr Aten Primaria. 14:53-60 2012 Full text (link to original source) Full text (in our servers)
  38. Sharma P, Murthy P, Bharath MM. Chemistry, metabolism, and toxicology of cannabis: clinical implications. Iran J Psychiatry. 2012 Abstract Full text (link to original source) Full text (in our servers)
  39. Goldschmidt L, Richardson GA, Willford JA, Severtson SG, Day NL. School achievement in 14-year-old youths prenatally exposed to marijuana. Neurotoxicol Teratol. 2012 Jan-Feb;34(1):161-7. Abstract
  40. Ilett KF, Hackett LP, Gower S, Doherty DA, Hamilton D, Bartu AE. Estimated dose exposure of the neonate to buprenorphine and its metabolite norbuprenorphine via breastmilk during maternal buprenorphine substitution treatment. Breastfeed Med. 2012 Aug;7:269-74. Abstract
  41. Day NL, Leech SL, Goldschmidt L. The effects of prenatal marijuana exposure on delinquent behaviors are mediated by measures of neurocognitive functioning. Neurotoxicol Teratol. 2011 Jan-Feb;33(1):129-36. Abstract
  42. Marchei E, Escuder D, Pallas CR, Garcia-Algar O, Gómez A, Friguls B, Pellegrini M, Pichini S. Simultaneous analysis of frequently used licit and illicit psychoactive drugs in breast milk by liquid chromatography tandem mass spectrometry. J Pharm Biomed Anal. 2011 May 15;55(2):309-16. Abstract
  43. Ranganathan M, Braley G, Pittman B, Cooper T, Perry E, Krystal J, D'Souza DC. The effects of cannabinoids on serum cortisol and prolactin in humans. Psychopharmacology (Berl). 2009 May;203(4):737-44. Abstract Full text (link to original source) Full text (in our servers)
  44. Garry A, Rigourd V, Amirouche A, Fauroux V, Aubry S, Serreau R. Cannabis and breastfeeding. J Toxicol. 2009;2009:596149. Abstract Full text (link to original source) Full text (in our servers)
  45. Campolongo P, Trezza V, Palmery M, Trabace L, Cuomo V. Developmental exposure to cannabinoids causes subtle and enduring neurofunctional alterations. Int Rev Neurobiol. 2009 Abstract
  46. El Marroun H, Tiemeier H, Steegers EA, Jaddoe VW, Hofman A, Verhulst FC, van den Brink W, Huizink AC. Intrauterine cannabis exposure affects fetal growth trajectories: the Generation R Study. J Am Acad Child Adolesc Psychiatry. 2009 Dec;48(12):1173-81. Abstract
  47. ABM - Comité de protocolos de la Academia médica de lactancia materna (Academy of Breastfeeding Medicine). Protocolo Clínico de la ABM #6: Lineamientos sobre la práctica de dormir al bebé junto con la madre y la lactancia materna Revisión, marzo de 2008. Breastfeeding Medicine 2008 Full text (link to original source) Full text (in our servers)
  48. ABM - The Academy of Breastfeeding Medicine Protocol Committee. ABM Clinical Protocol #6: Guideline on Co-Sleeping and Breastfeeding. Breastfeeding Medicine 2008 Abstract Full text (link to original source) Full text (in our servers)
  49. D'Souza DC, Ranganathan M, Braley G, Gueorguieva R, Zimolo Z, Cooper T, Perry E, Krystal J. Blunted psychotomimetic and amnestic effects of delta-9-tetrahydrocannabinol in frequent users of cannabis. Neuropsychopharmacology. 2008 Sep;33(10):2505-16. Abstract
  50. Goldschmidt L, Richardson GA, Willford J, Day NL. Prenatal marijuana exposure and intelligence test performance at age 6. J Am Acad Child Adolesc Psychiatry. 2008 Mar;47(3):254-263. Abstract
  51. Moore TH, Zammit S, Lingford-Hughes A, Barnes TR, Jones PB, Burke M, Lewis G. Cannabis use and risk of psychotic or affective mental health outcomes: a systematic review. Lancet. 2007 Abstract
  52. Schaefer C, Peters P, Miller RK. Drugs During Pregnancy and Lactation. Treatment options and risk assessment. Elsevier, second edition. London. 2007
  53. UNICEF UK. Compartiendo la cama con tu bebé. Guía para madres que amamantan. Folleto 2006 Full text (in our servers)
  54. Day NL, Goldschmidt L, Thomas CA. Prenatal marijuana exposure contributes to the prediction of marijuana use at age 14. Addiction. 2006 Sep;101(9):1313-22. Abstract
  55. Djulus J, Moretti M, Koren G. Marijuana use and breastfeeding. Can Fam Physician. 2005 Abstract Full text (link to original source) Full text (in our servers)
  56. Fernández-Ruiz J, Gómez M, Hernández M, de Miguel R, Ramos JA. Cannabinoids and gene expression during brain development. Neurotox Res. 2004 Abstract
  57. Fergusson DM, Horwood LJ, Northstone K; ALSPAC Study Team. Avon Longitudinal Study of Pregnancy and Childhood.. Maternal use of cannabis and pregnancy outcome. BJOG. 2002 Jan;109(1):21-7. Abstract
  58. Klonoff-Cohen H, Lam-Kruglick P. Maternal and paternal recreational drug use and sudden infant death syndrome. Arch Pediatr Adolesc Med. 2001 Abstract
  59. Fried PA, Smith AM. A literature review of the consequences of prenatal marihuana exposure. An emerging theme of a deficiency in aspects of executive function. Neurotoxicol Teratol. 2001 Jan-Feb;23(1):1-11. Review. Abstract
  60. Moretti ME, Lee A, Ito S. Which drugs are contraindicated during breastfeeding? Practice guidelines. Can Fam Physician. 2000 Sep;46:1753-7. Review. Abstract Full text (link to original source) Full text (in our servers)
  61. Fried PA, Watkinson B, Gray R. Growth from birth to early adolescence in offspring prenatally exposed to cigarettes and marijuana. Neurotoxicol Teratol. 1999 Abstract
  62. Fried PA. The Ottawa Prenatal Prospective Study (OPPS): methodological issues and findings--it's easy to throw the baby out with the bath water. Life Sci. 1995;56(23-24):2159-68. Abstract
  63. Day NL, Richardson GA, Goldschmidt L, Robles N, Taylor PM, Stoffer DS, Cornelius MD, Geva D. Effect of prenatal marijuana exposure on the cognitive development of offspring at age three. Neurotoxicol Teratol. 1994 Mar-Apr;16(2):169-75. Abstract
  64. Block RI, Farinpour R, Schlechte JA. Effects of chronic marijuana use on testosterone, luteinizing hormone, follicle stimulating hormone, prolactin and cortisol in men and women. Drug Alcohol Depend. 1991 Aug;28(2):121-8. Abstract
  65. Astley SJ, Little RE. Maternal marijuana use during lactation and infant development at one year. Neurotoxicol Teratol. 1990 Abstract
  66. Mendelson JH, Mello NK, Ellingboe J. Acute effects of marihuana smoking on prolactin levels in human females. J Pharmacol Exp Ther. 1985 Abstract
  67. Tennes K, Avitable N, Blackard C, Boyles C, Hassoun B, Holmes L, Kreye M. Marijuana: prenatal and postnatal exposure in the human. NIDA Res Monogr. 1985 Abstract Full text (link to original source) Full text (in our servers)
  68. Perez-Reyes M, Wall ME. Presence of delta9-tetrahydrocannabinol in human milk. N Engl J Med. 1982 Abstract
  69. Hale TW. Hale's Medications & Mothers' Milk. [Internet]. Springer Publishing Company; 1991-. Available from: None

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