Short answer: The Arimidex label says that if you miss a dose, take it as soon as you remember. If it is almost time for your next dose, skip the missed one and take the next at the usual time. Do not take two doses at the same time. Anastrozole has a half-life of about 50 hours.
| Situation | What the label says |
|---|---|
| Schedule | One 1 mg tablet once daily, with or without food (2.1) |
| Missed a dose | Take it as soon as you remember (17, Patient Information) |
| Almost time for the next dose | Skip the missed dose (17) |
| Doubling up | Never 2 doses at the same time (17) |
| Half-life | About 50 hours (12.3) |
Section 17 (Patient Counseling Information) says: if patients miss a dose, take it as soon as they remember; if it is almost time for the next dose, skip the missed dose and take the next regularly scheduled dose; do not take two doses at the same time. The Patient Information repeats this.
Example: you take anastrozole at 8 a.m. and remember at 1 p.m. Under the label you would take it at 1 p.m. If you remember at 7 a.m. the next day, you would skip it and take one tablet at 8 a.m.
The Arimidex label covers breast cancer in postmenopausal women, at 1 mg once daily. Using anastrozole to manage estradiol on TRT is outside the label, and prescribers often use a different schedule. The label's rule is written for 1 mg daily dosing, so ask your prescriber how it applies to your schedule.
Our estradiol-on-TRT article covers testing and why estradiol should not be pushed too low.
Anastrozole has a mean elimination half-life of about 50 hours (section 12.3), so the level falls slowly over a couple of days. One missed tablet does not drop it to zero, and doubling up the next day is not needed.
This page summarizes FDA labeling. It is not personalized medical advice; confirm what to do with your prescriber or pharmacist.