Nutrients/Active Ingredients: . Contain Vitamins A,C,E,F, and some vitamin K.  Also contains manganese, copper, potassium, iodine, and iron.
Uses by system and symptom: 
Cardiovascular: May lower blood pressure and improve circulation.
Digestive/Gastrointestinal: Used as a bitter tonic to help with digestion, IBS, diarrhea, gas liver and pancreas. Has been used for mild gingivitis.
Integumentary/Skin: Used as a skin tonic and antiseptic to prevent wound infection.
Skeletal: Used for arthritis.:
Urinary: Used as a diuretic
Nervous:  Used for anxiety and insomnia.
Immune: Has been used for Multiple Sclerosis.  Thought to have strong antibacterial and antifungal qualities
Common doses and preparation:  Leaves are used in cooking and seasoning. As a tea you would drink yarrow as a bitter tonic. Yarrow has a sweet aroma but sweet and bitter taste. spicy flavor compared to tarragon or anise. Often combined with  other herbs like tarragon, chervil, or parsley to cut the bitter taste if you are cooking with it. Often combined with dandelion and catnip for a stomach ache relief tea. Yarrow Tea:  (You can also add dandelion and catnip usually the amount is one heaping tablespoon of each).  It can be used to heal wounds but slower than a salve (over a 1-2 week period). 
Side Effects/Precautions/Interactions:   Not recommended to use during pregnancy or breastfeeding.  May increase risk of bleeding on people with bleeding disorders.  
* This statement has not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease. For educational purposes only. We recommend speaking with a physician or health care professions, especially if you have medical conditions, are pregnant or lactating, on medications, or use with children and infants.