Short answer: The Qsymia Medication Guide says that if you miss a dose, wait until the next morning to take your usual dose, and do not double your dose. Qsymia is taken once daily in the morning, and the label says to avoid evening doses because they can cause trouble sleeping. So a missed capsule is skipped, not taken late.
| Situation | What the label says |
|---|---|
| Schedule | Once daily in the morning, with or without food (2.2) |
| Missed a dose | Wait until the next morning for the usual dose (Medication Guide) |
| Doubling up | Do not double your dose (Medication Guide) |
| Evening dosing | Avoid, because of possible insomnia (2.2) |
| Phentermine half-life | About 20 hours (12.3) |
The Medication Guide says: if you miss a dose of Qsymia, wait until the next morning to take your usual dose. Do not double your dose.
Example: you take Qsymia at 7 a.m. and realize at 4 p.m. that you forgot. Under the label you would skip today and take your usual capsule tomorrow at 7 a.m.
Section 2.2 says to take Qsymia once daily in the morning and to avoid taking it in the evening because of the possibility of insomnia. The phentermine part has a half-life of about 20 hours (section 12.3), so a late dose is still active at bedtime.
The Qsymia label does not say how to restart after several missed days. That is a question for your prescriber.
Qsymia contains topiramate. Section 2.3 says the highest dose (15 mg/92 mg) should be stopped gradually, by taking it every other day for at least a week, because stopping suddenly could cause a seizure. Ask your prescriber before stopping or restarting.
This page summarizes FDA labeling. It is not personalized medical advice; confirm what to do with your prescriber or pharmacist.