Short answer: The tamoxifen Medication Guide says that if you forget a dose, take it when you remember, then take the next dose as usual. If it is almost time for the next dose, do not take extra to make up for the missed one. The Soltamox liquid label says the same. Tamoxifen has a half-life of about 5 to 7 days.
| Situation | What the label says |
|---|---|
| Schedule | 20 to 40 mg a day; more than 20 mg is split morning and evening (Dosage and Administration) |
| Forgot a dose | Take it when you remember, then the next dose as usual (Medication Guide) |
| Almost time for the next dose | Do not take extra to make up (Medication Guide) |
| Soltamox (liquid) | Same rule; never 2 doses at the same time (Medication Guide) |
| Half-life | About 5 to 7 days (Clinical Pharmacology) |
The Medication Guide for tamoxifen citrate tablets says: if you forget a dose, take it when you remember, then take the next dose as usual. If it is almost time for your next dose, or you remember at your next dose, do not take extra tablets to make up for the missed one.
The Soltamox (tamoxifen oral solution) Medication Guide gives the same rule and adds: do not take 2 doses at the same time, and call your healthcare provider if you are not sure about your dosing.
Example: you take 20 mg each morning and remember at 6 p.m. Under the label you would take it then and take tomorrow's dose as usual.
Tamoxifen has a terminal half-life of about 5 to 7 days (Clinical Pharmacology section of the tablet label). Levels fall slowly, so one late or skipped tablet changes them little.
The tamoxifen labels cover breast cancer treatment and risk reduction. Using it for gynecomastia or post-cycle therapy is outside the label, and schedules vary. The label's missed-dose rule assumes daily dosing; ask your prescriber how it fits your plan.
This page summarizes FDA labeling. It is not personalized medical advice; confirm what to do with your prescriber or pharmacist.