Herlet

No, Herlet does not cause ovarian cysts. It has not been reported by the patients who are taking this drug. However, the possibility of ovarian cysts formation by this drug because of long-term use in high doses cannot be denied.

No, Herlet is not a steroid. It contains letrozole which is a nonsteroidal competitive inhibitor of the aromatase enzyme. 

Herlet contains letrozole that works in breast cancer by blocking an enzyme (aromatase) which prevents the conversion of androgens (androstenedione and testosterone) to estrogens (estrone and estradiol) due to this levels of estrogen hormones drop in the body. The decrease in hormone levels leads to a reduction in tumor mass or delays the progression of tumor growth in some women. For an ovulation (infertility), it is presumed that Herlet works by increasing the sensitivity of ovary to follicular stimulating hormone (FSH) and also low level of estrogen hormones in the blood is detected by the brain which in turn increases the production of a follicular stimulating hormone (FSH) which causes induction of ovulation.

Yes Herlet can be taken along with tamoxifen at the same time because tamoxifen decreases levels of letrozole by unknown mechanism. Hence taking Herlet with tamoxifen at the same time should be avoided.

Yes, Herlet can be taken together with vitex agnus-castus. No clinically significant drug interaction has been reported between them. However, if you feel any discomfort after taking this drug along with vitex then do not hesitate to inform your doctor.