How to take Phentermine

Taken once daily. Everything below is quoted from the FDA label rather than summarised, because a dosing instruction restated twice stops being the label and the detail that goes missing is always the number. What this page adds to the label is the part the label has no reason to carry: what a mistake costs.

How do you take Phentermine, and what does getting it wrong cost?

Administered before breakfast or 1 to 2 hours after breakfast for appetite control. Late evening administration should be avoided (risk of insomnia). Dosage should be individualized to obtain an adequate response with the lowest effective dose. Store at 20° to 25°C (68° to 77°F). 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

Administered before breakfast or 1 to 2 hours after breakfast for appetite control. Late evening administration should be avoided (risk of insomnia). Dosage should be individualized to obtain an adequate response with the lowest effective dose.

Storage

Store at 20° to 25°C (68° to 77°F).

Read from FDA prescribing information for phentermine hydrochloride on 2026-08-28. 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.

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: Administered before breakfast or 1 to 2 hours after breakfast for appetite control. Late evening administration should be avoided (risk of insomnia). Dosage should be individualized to obtain an adequate response with the lowest effective dose.

Everything on Phentermine

Last updated 2026-08-28 — the FDA label this page quotes