Health Canada
Symbol of the Government of Canada
Drugs and Health Products

Monograph: Thuja - Oral

Help on accessing alternative formats, such as Portable Document Format (PDF), Microsoft Word and PowerPoint (PPT) files, can be obtained in the alternate format help section.

Date: 2018-08-27


Thuja occidentalis (Germplasm Resources Information Network Taxonomy)

Proper Name(s)

Thuja occidentalis ( USDA 2008 )

Common Name(s)

Source Material

Herb top ( Unavailable )

Route Of Administration


Dosage Form(s)

Those suited to the allowable route(s) of administration. This monograph is not intended to include food-like dosage forms such as bars, chewing gums or beverages.

Use(s) or Purpose(s)

Statement(s) to the effect of:

Traditionally used in Herbal Medicine as an expectorant to help relieve bronchial mucus buildup (catarrh).  (Hoffmann 2003, Williamson 2003, BHP 1983, Felter and Lloyd 1983[1898])



Dose(s): 1 Day per day

See Appendix 1 for examples of appropriate dosage preparations and frequencies of use, according to cited references. The purpose of Appendix 1 is to provide guidance to industry.

Duration of use

For occasional use only.  (Brinker 2001, McGuffin et al. 1997)

Risk Information

Statement(s) to the effect of:

Caution(s) and Warning(s):
  • Consult a health care practitioner/health care provider/health care professional/ doctor/ physician if symptoms persist or worsen.
  • Consult a health care practitioner/health care provider/health care professional/doctor/ physician prior to use if you are breastfeeding or taking other herbs containing thujone (e.g. wormwood, sage, tansy, and juniper).  (Brinker 2010)

Do not use this product if you are pregnant.  (Hoffmann 2003, Brinker 2001, BHP 1983)

Known Adverse Reaction(s):
No statement is required

Non-medicinal ingredients

Must be chosen from the current Natural Health Products Ingredients Database and must meet the limitations outlined in the database.


  • The finished product specifications must be established in accordance with the requirements described in the NHPD Quality of Natural Health Products Guide.
  • The medicinal ingredient must comply with the requirements outlined in the Natural Health Products Ingredient Database (NHPID).

References cited

  • Berardi RR, DeSimone EM, Newton GD, Oszko MA, Popovich NG, Rollins CJ, Shimp LA, Tietze KJ, editors. Handbook of Nonprescription Drugs: An Interactive Approach to Self-Care, 13th edition. Washington (DC): American Pharmaceutical Association; 2002.
  • BHP 1983: British Herbal Pharmacopoeia. Cowling (GB): British Herbal Medical Association; 1983.
  • Brinker F. 2001. Herb Contraindications and Drug Interactions, 3rd edition. Sandy (OR): Eclectic Medical Publications.
  • Brinker F. 2010. Online Updates and Additions to Herb Contraindications and Drug Interactions, 3rd edition. Sandy (OR): Eclectic Medical Publications. [Updated 2010 July 13; Accessed 2013 January 30]. Available from:
  • Felter HW, Lloyd JU. 1983. King's American Dispensatory, Volume 2, 18th edition. Sandy (OR): Eclectic Medical Publications [Reprint of 1898 original].
  • Hoffmann D. 2003. Medical Herbalism: The Science and Practice of Herbal Medicine. Rochester (VT): Healing Arts Press.
  • McGuffin M, Hobbs C, Upton R, Goldberg A, editors. 1997. American Herbal Products Association's Botanical Safety Handbook. Boca Raton (FL): CRC Press.
  • McGuffin M, Kartesz JT, Leung AY, Tucker AO, editors. 2000. Herbs of Commerce, 2nd edition. Austin(TX): American Herbal Products Association.
  • Rietjens IM, Martena MJ, Boersma MG, Spiegelenberg W, Alink GM. Molecular mechanisms of toxicity of important food-borne phytotoxins. Molecular Nutrition & Food Research 2005;49(2):131-158.
  • USDA 2008: ARS, National Genetic Resources Program. Germplasm Resources Information Network (GRIN). National Germplasm Resources Laboratory, Beltsville (MD). [Accessed 2008-01-21]. Available at
  • Williamson EM. Potter's Herbal Cyclopaedia: The Authoritative Reference work on Plants with a Known Medical Use. Saffron Walden (UK): The C.W. Daniel Company Limited; 2003.

References reviewed

  • Burkhard PR, Burkhardt K, Haenggeli CA, Landis T. Plant-induced seizures: reappearance of an old problem. Journal of Neurology 1999;246(8):667-670.
  • EC-SCF 2003: European Commission Scientific Committee on Food. Opinion of the Scientific Committee on Thujone. Brussels (B): European Commission Health and Consumer Protection Directorate-General. Scientific Committee on Food. Scientific Committee on Thujone; February 6, 2003, pp. 1-11. [Accessed 2008-04-25]. Available at:
  • EEC 1988: European Economic Committee. Council Directive 88/388/EEC on the approximation of the laws of the Member States relating to flavourings for use in foodstuffs and to source materials for their production. Brussels (B): European Economic Committee Council Directive 88/388/EEC of 22 June 1988. [Accessed 2008-04-25]. Available at:
  • Stafstrom CE. Seizures in a 7-month-old child after exposure to the essential plant oil thuja. Pediatric Neurology 2007;37(6):446-448.

Appendix 1: Examples of appropriate dosage preparations, frequencies of use and directions for use


Dried aerial parts:

1 - 2 g, 3 times per day (Williamson 2003; BHP 1983)


1 - 2 g dried aerial parts, 3 times per day (Williamson 2003; BHP 1983)

Directions for use:

Pour 250 ml of boiling water over dried aerial parts and steep for 10-15 minutes (Hoffmann 2003).