There is no clinical experience of overdose. Letrozole is known to show only a minor degree of acute toxicity in animal studies. No clinical data are available for specific doses of letrozole that may result in life-threatening symptoms.
No specific antidote is available. In general, in such cases it is necessary to carry out supportive, symptomatic therapy and monitoring of basic vital signs of the body.
Use during pregnancy and lactation
Taking into account the experience of letrozole use in humans and single cases of congenital malformations (fusion of small labia, external genitalia of intermediate type), letrozole may cause congenital malformations when used during pregnancy. Animal studies have shown reproductive toxicity of the drug.
Letrozole is contraindicated during pregnancy.
It is not known whether letrozole or its metabolites are excreted with breast milk. A risk to neonates/infants should not be excluded.
Thus letrozole is contraindicated during breastfeeding.
Perimenopausal women and women of reproductive age
Letrozole should only be used in women with clearly established postmenopausal status. Spontaneous abortions or congenital anomalies have been reported in neonates whose mothers were taking letrozole. In view of the reported recovery of ovarian function in women treated with letrozole, despite a clear postmenopausal status at the beginning of therapy, the physician should discuss with the patient adequate contraceptives, if necessary.