Sorry to cut and paste. This info came with the vitex liquid I used-- explains it pretty well i thought?
Vitex Agnus Castus Hormone Balance
Greenridge Vitex agnus castus, more commonly known as chaste tree. Natural hormone balance for women. An effective herb for regulating female hormones and may assist with the relief of menstrual symptoms. An important herb for helping to balance female hormones by regulating the pituitary gland. Helps with a variety of hormonal disorders especially those caused by excess oestrogen. Needs to be taken for at least 3 months. Ideal for after having a baby, to help balance hormone levels up again, for those with an erratic cycle (break through bleeding, spotting and a short cycle - say getting your period from day 20-25, rather than on day 28) and for PMT. Do not use in cases of high progesterone, as this herb can help to naturally increase progesterone levels. Suitable for vegans and vegetarians.
Common Uses
Hormone imbalances, PMS, cramping, fluid retention, mood swings, depression, tender swollen breasts, hormonal weight gain, bloatedness, hormonal headaches, excessive bleeding, loss of libido, hot flushes, night sweats, thinning of vaginal mucosa, alternative to HRT, hormonal acne, increases progesterone and luteinizing hormone production, creates normal balance between estrogen and progesterone, normalizes heavy, frequent or non existent menstrual flow, help reduce prolactin levels which may be a contributor to infertility.
Suggested Dosage
Adult take 2 ml in the morning, in a small quantity of water or juice. Shake well before use. Do not take erratically. To produce a regulatory effect, this herb MUST be taken every day of the month (even when you have your period) Do not miss a day, once started. We suggest starting on Day 1, the 1st day of true bleeding.
Health Information
Vitex or Chaste Tree is a hormone regulating herb used especially for, but not restricted to, women. Indications include menstrual disorders stemming from estrogen/progesterone imbalance. Researchers have been investigating Vitex for over 30 years in the UK and Germany and it is clear that the berries have a distinct effect on the reproductive system. This includes PMS/PMT and estrogen related infertility. Studies also indicate Vitex may be useful to stimulating both production and secretion of breast milk. Since there are no reported harmful effects, Vitex should be considered a first line treatment before hormone therapies are undertaken. It may also be considered in peripheral hormone imbalance conditions such as acne and premenstrual herpes simplex. Many women with menstrual cycle irregularities are not producing enough progesterone during the 2nd half of their cycle. This means that estrogen continues to be the dominant hormone. This can lead to a shortening of the luteal phase, by as much as 50%. When this occurs, women can suffer from premenstrual syndrome, a lack of periods, infertility and also too frequent or heavy periods. Vitex, which does not contain hormones, acts to correct the deficiency of progesterone by actually working on the pituitary gland - the gland that produces the regulatory hormones influencing progesterone and estrogen production. Vitex influences the pituitary to increase the secretion of luteinizing hormone (LH), the hormone responsible for increasing progesterone secretion during the luteal phase. This results in a normal balance between estrogen and progesterone. Another problem affecting many women with "luteal phase defect" is the over production of another pituitary hormone known as prolactin. High levels of prolactin during the late stages of the luteal phase can contribute to breast tenderness and pain as well as infertility. Vitex has been shown to actually reduce prolactin secretion in women overproducing it during their menstrual cycle. Used for an average of 3 months in a 1 a day dosage, vitex has led to a normalisation of mid-luteal phase progesterone levels and lengthening of the luteal phase.
Ingredients
Each 1ml contains Vitex agnus castus (chaste tree) extract equivalent to 200mg dry berries. Contains non-active alcohol (ethanol) 450mcL/ml. No added gluten, lactose, yeast, sugar, artificial flavours or sweeteners.
Safety Information
Keep out of reach of children. If symptoms persist, consult your healthcare professional. Do not take if pregnant of breastfeeding. Contains alcohol. Note from Leanne: A large percentage of women notice increased breast tenderness the first month they take this herb. This happens because of the regulatory effect this herb has on the pituitary gland, the gland that regulates prolactin levels. Because of this action, many women notice this initially.
I haven't been doing OPK so I'm not sure when/if I am ovulating and thought maybe I would try them but since I've not had a period in a long time I don't know where to start. 
I just started using it to help me (and my future bean lol) so we'll see how it goes. It also works well if you take folic acid and B6 with it (from what i've read.. and believe me ive read a LOT). 
