Report on Yarrow Side Effects and Usage by AskDocWeb


Natural health supplements sometimes have unexpected side effects or interactions with medication that can lead to adverse reactions that are sometimes life threatening. The following is a list of cautions that you should be aware of before using Yarrow (Achillea millefolium). These are referred to as drug/herb interactions.

Warning 1 – Contraindications: Epilepsy, pregnancy and lactation. Yarrow is believed to effect the menstrual cycle and may cause miscarriage. Consuming large amounts of yarrow could cause low fetal birth weights. Until more is known about the safety of using yarrow during nursing it is NOT recommended.

Warning 2 – Anticoagulants/Antiplatelets: (Major interaction) Yarrow may increase bleeding when used concurrently with anticoagulants / antiplatelet drugs. Experts recommend avoiding concurrent use.

Warning 3 – Antihypertensives: Using yarrow may result in increased hypotension. Experts recommend avoiding concurrent use.

Warning 4 – Central Nervous System Depressants: may result in increased CNS depression. Experts recommend avoiding concurrent use.

Warning 5 – Allergies: Those with allergies to ragweed, chrysanthemums, marigolds, daisies or any plant in the Asteraceae/Compositae family should check with their doctor before using yarrow.

Warning 6 – Surgery: Yarrow may increase bleeding during and after surgery. If you use yarrow, discontinue use 2 weeks before a scheduled surgery.

Warning 7 – Lithium: (Moderate interaction) Yarrow may decrease the body’s ability to get rid of lithium. This could potentially result in too much lithium in the body resulting is serious side effects. If you take lithium talk to your doctor before using yarrow.

Warning 8 – PPIs and Antacids: (Minor interaction) Yarrow interacts with antacids and medications that decrease stomach acid. Yarrow may also increase the production of stomach acid. If you use antacids or take PPIs talk to your doctor before using yarrow.

Warning 9 – Fertility: Yarrow may affect the human male’s ability to produce health sperm and reproduce. In a study published in a 2004 issue of the journal “Reproductive Toxicology,” Paulo Dalsenter and colleagues from Brazil concluded that large amounts of yarrow extract affected the sperm of male rats. That study showed yarrow extract created a significant increase in the percentage of abnormal sperm produced by male rats. Although human trials were not performed, this suggests that yarrow may have the same effect on human males.

Used as a natural health remedy: Yarrow is used both internally and externally for a verity of conditions and diseases:


  • to stop bleeding from hemorrhoids
  • to stop bleeding from wounds
  • as a sitz bath for cramp-like conditions
  • young leaves and flowers are used in salads
  • as a cosmetic cleanser
  • yarrow oil is used in shampoos


  • appetite stimulant
  • to induce sweating
  • intestinal gas (flatulence)*
  • reduce heavy menstrual bleeding and pain
  • relieve fever*
  • increase urine flow
  • relieve muscle spasms
  • common cold*
  • diarrhea*
  • bloating*
  • hay fever*
  • upset stomach*
  • leaves are chewed to relieve toothache
  • as an ingredient in snuff

As a home remedy for toothache, when dental pain begins, chew the plant’s feathery leaves and put them on the affected area. It acts very quickly and offers temporary relief for teeth and gum problems.

Yarrow should not be used to treat large, deep, or infected wounds, all of which require medical attention.

Side Effects of Yarrow

Most adults have no side effects from using yarrow. A small percentage of people may experience one or more of the following:

  1. skin rash
  2. drowsiness
  3. increased urination

Other side effects may also occur when using Yarrow. (See form below)

Return to the Herb List.

For questions and answers about the side effects of herbs see the Herb Forum

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