In the treatment with Tamoxifen, the most frequent adverse reactions associated with its anti-estrogenic effect, manifested in the form of paroxysmal sensations of heat (tides), vaginal bleeding or discharge, itching in the genital area, alopecia, pain in the area of the lesion; ossaly, increase in body weight.
Less frequently or rarely, the following adverse reactions were observed: fluid retention, anorexia, nausea, vomiting, constipation, fatigue, depression, confusion, headache, dizziness, drowsiness, fever, skin rash, visual impairment, including corneal changes, cataracts , retinopathy and, retrobulbar neuritis.
At the beginning of treatment, local exacerbation of the disease is possible - an increase in the size of soft tissue formations,sometimes accompanied by severe erythema of affected areas and adjacent areas - which usually occurs within 2 weeks.
The likelihood of thrombophlebitis and thromboembolism may increase.
Sometimes transient leukopenia and thrombocytopenia can occur, as well as an increase in the level of hepatic enzymes, very rarely accompanied by more severe impairments of liver function, such as fatty liver infiltration, cholestasis and hepatitis.
In some patients with bone metastases at the beginning of treatment, hypercalcemia was observed.
Tamoxifen causes amenorrhea or irregularity of menstrual periods in premenopausal women, as well as reversible development of cystic ovarian tumors.
With long-term treatment with Tamoxifen, changes, endometrium, including hyperplasia, polyps and in some cases - endometrial cancer, as well as the development of uterine fibroids, can be observed.