What if you miss a dose of Phentermine?

How to take Phentermine

Taken once daily at the usual dose; the label also allows half a tablet (18.75 mg) once or twice a day. Everything below is quoted from the FDA label rather than summarized, because a dosing instruction restated twice stops being the label and the detail that goes missing is always the number.

How do you take Phentermine?

The usual adult dose is one tablet (37.5 mg) daily, as prescribed by the physician, administered before breakfast or 1 to 2 hours after breakfast. The dosage may be adjusted to the patient’s need. For some patients, half tablet (18.75 mg) daily may be adequate, while in some cases it may be desirable to give half tablets (18.75 mg) two times a day. Phentermine is not recommended for use in pediatric patients ≤ 16 years of age. Late evening medication should be avoided because of the possibility of resulting insomnia. Store at 20° to 25°C (68° to 77°F) [See USP Controlled Room Temperature]. The label gives no missed-dose instruction here, which is itself the answer: ask the prescriber rather than guess.

What the label says

When to take it

The usual adult dose is one tablet (37.5 mg) daily, as prescribed by the physician, administered before breakfast or 1 to 2 hours after breakfast. The dosage may be adjusted to the patient’s need. For some patients, half tablet (18.75 mg) daily may be adequate, while in some cases it may be desirable to give half tablets (18.75 mg) two times a day. Phentermine is not recommended for use in pediatric patients ≤ 16 years of age. Late evening medication should be avoided because of the possibility of resulting insomnia.

Storage

Store at 20° to 25°C (68° to 77°F) [See USP Controlled Room Temperature].

Read from FDA prescribing information for phentermine hydrochloride on 2026-09-12. Labels are revised; the date is there so you can tell how old this reading is. Information only, not medical advice — dosing is a decision for the clinician who wrote the prescription.

No clinician has reviewed this page. Label and trial statements are quoted from the FDA label or the trial cited beside them. General guidance is marked as such, and every price carries the date it was verified. That is sourcing, not medical review. What we do and do not check · Who checked the price

Taking Phentermine, answered

What if you miss a dose of Phentermine?: The label gives no missed-dose instruction for Phentermine, so this page does not invent one — that is a question for the prescriber. What the label does set is the timing, and it is specific: The usual adult dose is one tablet (37.5 mg) daily, as prescribed by the physician, administered before breakfast or 1 to 2 hours after breakfast. The dosage may be adjusted to the patient’s need. For some patients, half tablet (18.75 mg) daily may be adequate, while in some cases it may be desirable to give half tablets (18.75 mg) two times a day. Phentermine is not recommended for use in pediatric patients ≤ 16 years of age. Late evening medication should be avoided because of the possibility of resulting insomnia.

Everything on Phentermine

Last updated 2026-09-12 — the FDA label this page quotes. Read and dated by Alex Seot.