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Yarrow
Achillea Millefolium

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Toxic Lookalikes of Yarrow (Achillea millefolium)

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1. Poison Hemlock (Conium maculatum)

- Leaves: Fern-like and finely divided, similar to yarrow.

- Key differences:

- Smooth, hollow stems with purple blotches.

- Strong, unpleasant smell (like mouse urine).

- Grows much taller than yarrow.

- Highly toxic—fatal if ingested.

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2. Water Hemlock (Cicuta spp.)

- Leaves: Also finely divided and can be confused with yarrow.

- Key differences:

- Often grows in wet areas (marshes, ditches).

- White umbrella-like flower clusters (like yarrow’s), but stems are grooved and sometimes have purple streaks.

- Extremely toxic—one of North America’s most poisonous plants.

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3. Queen Anne’s Lace / Wild Carrot (Daucus carota)

This herb offers support in plant medicine, but must be taken with caution and understanding. 

- Leaves: Fern-like, also finely divided.

- Key differences:

- Umbrella-shaped white flower cluster with a tiny dark purple floret in the center.

- Stems hairy (yarrow’s are smooth).

References

Barley, Shanta. The University of Australia. 2000-year-old pills found in Greek shipwreck. September 2010. The New Scientist 207(2778):14-14. DOI:10.1016/S0262-4079(10)62251-8

 

Stojanovic G. et al., “In vitro antimicrobial activity of extracts of four Achillea species …” J Ethnopharmacol. 2005;101(1‑3):185–190. DOI:10.1016/j.jep.2005.04.026

 

Safayhi H, Sabieraj J, Sailer ER, Ammon HP. Chamazulene: an antioxidant-type inhibitor of leukotriene B4 formation. Planta Med. 1994 Oct;60(5):410-3. doi: 10.1055/s-2006-959520. PMID: 7997466.D’Anneo A. et al., “Antioxidant, anti-inflammatory, and antibacterial properties … against H. pylori.” Antioxidants 2022;11:1849.

 

Benedek B et al. (2007). Yarrow (Achillea millefolium) – pharmacology and clinical potential. Phytotherapy Research 21(3): 230–237.

 

Clinical Trials

  1. Ayoobi F, Moghadam-Ahmadi A, Amiri H, Vakilian A, Heidari M, Farahmand H, Fathollahi MS, Fatemi I, Shafiei SA, Alahtavakoli M, Shamsizadeh A. Achillea millefolium is beneficial as an add-on therapy in patients with multiple sclerosis: A randomized placebo-controlled clinical trial. Phytomedicine. 2019 Jan;52:89-97. doi: 10.1016/j.phymed.2018.06.017. Epub 2018 Jun 27. PMID: 30599916.Jenabi &

  2. Jenabi E, Fereidoony B. Effect of Achillea Millefolium on Relief of Primary Dysmenorrhea: A Double-Blind Randomized Clinical Trial. J Pediatr Adolesc Gynecol. 2015 Oct;28(5):402-4. doi: 10.1016/j.jpag.2014.12.008. Epub 2014 Dec 23. PMID: 26238568.

  3. Daneshvar-Ghahfarokhi S, Ahmadinia H, Sadeghi T, Basirat E, Mohammadi-Shahrokhi V. Achillea millefolium capsule improved liver enzymes and lipid profile compared to placebo in patients with type 2 diabetes: a double-blind randomized clinical trial. BMC Nutr. 2025 Jan 24;11(1):21. doi: 10.1186/s40795-025-01005-5. PMID: 39856724; PMCID: PMC11761196.

Interactions / Cautions

  • Avoid during pregnancy—potential uterine-stimulating effects.

  • Caution with known allergies to the Asteraceae family.

  • May potentiate anticoagulant medications (theoretical).

  • Avoid overuse—potential for skin irritation in sensitive individuals with topical supports.

  • Always consult with your healthcare provider before trying herbs.

St. John's Wort
Hypericum perforatum

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TOXIC LOOK-A-LIIKES

1. Ragwort (Senecio jacobaea)

Appearance: Similar yellow flowers in clusters.
Key Differences: Ragwort has a more robust, hairy stem and different leaf shapes (ragged, deeply lobed leaves), while St. John’s wort has opposite leaves with translucent dots when held up to light.
Toxicity: Contains pyrrolizidine alkaloids, which can cause liver damage in livestock and potentially humans.

2. Tansy (Tanacetum vulgare)

Appearance: Bright yellow, button-like flowers in flat clusters.
Key Differences: Tansy has a strong aromatic smell and fern-like, deeply divided leaves, while St. John’s wort has small, oval leaves with transparent dots.
Toxicity: Contains thujone and can be toxic if consumed in large amounts.

3. Common Groundsel (Senecio vulgaris)

Appearance: Yellow flowers that turn into white, fluffy seed heads.
Key Differences: Groundsel has small, dandelion-like seed heads and lacks the characteristic perforated leaves of St. John’s wort.
Toxicity: Like ragwort, it contains pyrrolizidine alkaloids and is hepatotoxic.

4. Creeping St. John’s Wort (Hypericum calycinum) 

Appearance: Also has yellow flowers, though they are much larger and more showy.

Key Differences: Typically used as an ornamental groundcover; not considered toxic, but it’s not the medicinal St. John’s wort used in herbal medicine.

Toxicity: Generally safe, though not used medicinally.

References

Video of Herbal Effects

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1. Klemow KM, Bartlow A, Crawford J, et al. Medical Attributes of St. John’s Wort (Hypericum perforatum) In: Benzie IFF, Wachtel-Galor S, editors. Herbal Medicine: Biomolecular and Clinical Aspects. 2nd edition. Boca Raton (FL): CRC Press/Taylor & Francis; 2011. Chapter 11. Available from: https://www.ncbi.nlm.nih.gov/books/NBK92750/

 

2. Bone, Kerry, and Simon Mills. Principles and Practice of Phytotherapy: Modern Herbal Medicine, 2nd edition. Churchill Livingstone/Elsevier Health Sciences, December 31, 2012. ISBN 978‑0‑443‑06992‑5 

 

Video of  Herbal Evidence

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  1. Sean Ó Súilleabháin, Irish folklore archivist, noted its role in protective home charms.

  2. W. B. Yeats wrote about midsummer herbs in his documentation of Irish spiritual traditions.

  3. Dáithí Ó hÓgáin, in The Lore of Ireland, refers to St. John’s Wort as an "herb of power" used in seasonal rituals.

  4. Irish Folklore Commission archives (1930s–1950s) contain oral histories mentioning St. John’s Wort in local cures and midsummer rites.


 

Meta Analyses

1. Linde K, Ramirez G, Mulrow CD, Pauls A, Weidenhammer W, Melchart D. St John’s wort for depression—an overview and meta-analysis of randomized clinical trials. BMJ. 1996 Aug 3;313(7052):253–8. doi:10.1136/bmj.313.7052.253

2. Linde K, Mulrow CD, Berner M, Egger M. St John’s wort for depression: Meta-analysis of randomized controlled trials. Br J Psychiatry. 2005 Feb;186(2):99–107. Also published as Cochrane Review CD000448 (2005; updated 2008).

3. Linde K, Berner MM, Kriston L. St John’s wort for major depression. Cochrane Database Syst Rev. 2008 Oct 8;(4):CD000448.

4. Ng QX, Venkatanarayanan N, Ho CY. Clinical use of Hypericum perforatum (St John’s wort) in depression: A meta-analysis. J Affect Disord. 2017 Mar 1;210:211–221. doi:10.1016/j.jad.2016.12.048

5. Zhao X, Zhang H, Wu Y, Yu C. The efficacy and safety of St. John’s wort extract in depression therapy compared to SSRIs in adults: A meta-analysis of randomized clinical trials. Adv Clin Exp Med. 2023 Feb;32(2):151–161. doi:10.17219/acem/152942

6. Cui YH, Zheng Y. A meta-analysis on the efficacy and safety of St John's wort extract in depression therapy in comparison with selective serotonin reuptake inhibitors in adults. Neuropsychiatr Dis Treat. 2016 Jul 11;12:1715–1723. doi:10.2147/NDT.S106752

St. John’s Wort: Cautions & Interactions

 Pregnancy & Postpartum

  • There is not enough data to confirm safety during pregnancy.

  • It may be helpful during postpartum recovery, as long as no other medications are being taken.

⚠️Interactions & Warnings

Photosensitivity

  • High doses may increase sensitivity to sunlight. Use caution with sun exposure.

Liver Enzyme Interactions (CYP450)

St. John’s Wort stimulates liver enzymes, especially CYP3A4, which causes faster breakdown of many medications, lowering their effectiveness.

Avoid combining with:

  • Blood thinners like warfarin – St. John’s Wort decreases its effect, increasing risk of clotting.

  • Blood pressure medications, especially calcium channel blockers like nifedipine and verapamil – St. John’s Wort reduces how well these drugs work.

  • Certain statins – St. John’s Wort lowers plasma levels of simvastatin, but has no known effect on pravastatin.

  • Proton pump inhibitors (PPIs) like omeprazole and esomeprazole – Effectiveness is reduced when combined with St. John’s Wort.

  • Opioid pain medications, especially oxycodone – SJW reduces their concentration, making them less effective.

  • Antibiotics, antifungals, and antivirals – There are many potential interactions. Avoid use while taking these.

  • Oral contraceptive pills (OCPs) – SJW increases metabolism, lowering effectiveness. May lead to breakthrough bleeding or unintended pregnancy.

 Mental Health Medications

  • Use extreme caution with SSRIs, SNRIs, and tricyclic antidepressants (TCAs).
    Combining them with St. John’s Wort may increase serotonin levels too much, risking serotonin syndrome.
    Careful monitoring is required if combining.
    Note: Drinking SJW as a nutritive tea may be less concerning than tincture or capsule forms.

🌙 Melatonin

  • Combining St. John’s Wort with melatonin may lead to excessive drowsiness or a "hangover" feeling after sleep.

  • There is not enough research to confirm this, so use caution.

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This herbal education is not intended to treat, diagnose, cure, or prevent disease states; their efficacy is not regulated by any governing body in the US, but quality is regulated by local Departments of Agriculture and/or the FDA with GMP labeling. These herbs are intended to support health and your body’s innate ability to maintain homeostasis (balance). Always contact your healthcare providers if on medications and interested in trying herbs.

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