- Male patients should be willing to use barrier contraception. Male patients should be asked to use barrier contraceptives (i.e., by use of condoms) during sex with all of their female partners during the trial and for a washout period of 3 months. Patients should refrain from donating sperm from the start of dosing until 6 months after discontinuing osimertinib treatment. If male patients wish to father children they should be advised to arrange for freezing of sperm samples prior to the start of osimertinib treatment.