Short answer: Both are appetite suppressants approved for short-term use, a few weeks, alongside a lower-calorie plan.12 Both labels give the schedule as IV. Diethylpropion 25 mg is taken three times a day an hour before meals; Lomaira (phentermine 8 mg) three times a day half an hour before meals. Neither label gives side-effect percentages or reports a trial against the other.
| Diethylpropion | Phentermine (Lomaira) | |
|---|---|---|
| Approved for | Short-term add-on to a calorie-restricted plan, starting BMI of 30 or more1 | Short-term add-on to exercise, behavior change and fewer calories, starting BMI of 30 or more, or 27 or more with risk factors such as controlled high blood pressure, diabetes or high cholesterol2 |
| Label dose | 25 mg three times daily, one hour before meals, and midevening if desired for night hunger1 | 8 mg three times a day, half an hour before meals; scored for half tablets; late evening doses avoided2 |
| DEA schedule | Schedule IV1 | Schedule IV2 |
| Keep going only if | Satisfactory weight loss in the first 4 weeks, for example at least 4 pounds1 | The label says the dose is not raised when the appetite effect wears off; the drug is stopped instead2 |
| Boxed warning | None1 | None2 |
Both labels warn about pulmonary hypertension, a rare and often fatal lung disease, and heart valve disease, and both say to stop the drug rather than raise the dose when tolerance develops.12 Both say it may impair driving. The diethylpropion label adds that it may increase seizures in some people with epilepsy, and that rare hallucinations and toxic psychosis have been reported.1 The Lomaira label says people on insulin or oral diabetes medicines may need a lower dose of those, and warns against drinking alcohol with it.2
Both list people who should not take them, including those with an overactive thyroid, glaucoma, a history of drug abuse, or use of an MAO inhibitor in the past 14 days.12 Which, if either, fits is for your prescriber. More detail: diethylpropion side effects, Lomaira side effects, the diethylpropion and Lomaira dosing schedules, and Lomaira vs Qsymia: what is the difference?.