Short answer: Both are appetite suppressants approved for short-term use, a few weeks, alongside a lower-calorie plan.12 The phendimetrazine package label prints CIII; the Lomaira label says phentermine is Schedule IV. Phendimetrazine 35 mg is taken two or three times a day; Lomaira 8 mg three times a day. Neither label gives side-effect percentages or reports a trial against the other.
| Phendimetrazine | Phentermine (Lomaira) | |
|---|---|---|
| Approved for | Short-term add-on to a calorie-restricted plan, starting BMI of 30 or more, used on its own1 | Short-term add-on to exercise, behavior change and fewer calories, starting BMI of 30 or more, or 27 or more with risk factors2 |
| Label dose | 35 mg two or three times a day, one hour before meals; sometimes half a tablet; no more than 2 tablets three times a day1 | 8 mg three times a day, half an hour before meals; scored for half tablets; late evening doses avoided2 |
| DEA schedule | CIII printed on the package label1 | Schedule IV2 |
| Heart valve disease | Reported with some appetite suppressants, no cases with phendimetrazine alone1 | Reported with phentermine plus fenfluramine or dexfenfluramine, and rarely with phentermine alone2 |
| Boxed warning | None1 | None2 |
Both labels warn about pulmonary hypertension, a rare and often fatal lung disease, say to stop the drug rather than raise the dose when tolerance develops, and say not to combine it with other weight-loss drugs.12 The phendimetrazine label says treatment continues only with satisfactory weight loss in the first 4 weeks, and that stopping suddenly after long high-dose use causes extreme fatigue and depression.1 The Lomaira label warns against drinking alcohol with it and says it was not studied in kidney impairment.2
Both labels say people with diabetes may need their insulin or other diabetes medicine changed.12 Which, if either, fits is for your prescriber. More detail: phendimetrazine side effects, Lomaira side effects, the phendimetrazine and Lomaira dosing schedules, and Diethylpropion vs phentermine: how do the two appetite suppressants differ?.