DIDREX vs FASTIN

Independent side-by-side comparison.

Rated against independent regulatory sources·Last updated August 12, 2026·How we rate

Possible drug interaction. DIDREX and FASTIN are different prescription medicines. Combining or switching between them can cause interactions — talk to a pharmacist or prescriber before making changes. This page is not medical advice.

Attribute	DIDREX	FASTIN
Rating	64/100	70/100
Pharmacy pays	—	~$2.54 /30
Type	RX	RX
Active ingredient	BENZPHETAMINE HYDROCHLORIDE	PHENTERMINE HYDROCHLORIDE
Manufacturer	Pfizer	Glaxosmithkline
Dosage forms	Tablet	Capsule
Drug class	Sympathomimetic Amine Anorectic	Sympathomimetic Amine Anorectic
Boxed warning	None	None
Treats	Obesity	Obesity

didrex fastin

Rating

64/100

70/100

Pharmacy pays

—

~$2.54 /30

Type

Active ingredient

BENZPHETAMINE HYDROCHLORIDE

PHENTERMINE HYDROCHLORIDE

Manufacturer

Pfizer

Glaxosmithkline

Dosage forms

Tablet

Capsule

Drug class

Sympathomimetic Amine Anorectic

Boxed warning

None

Treats

Obesity

Frequently asked questions

Which is better-rated, Didrex or Fastin?

By our independent rating, Fastin scores higher — 3.5 vs 3.2 out of 5 for Didrex. Ratings are based on FDA regulatory (recall-safety) data.

What is the difference between Didrex and Fastin?

Didrex contains Benzphetamine Hydrochloride, while Fastin contains Phentermine Hydrochloride — they have different active ingredients.

Ratings are based on FDA regulatory (recall-safety) data. This comparison is for general reference only — not medical advice. Always consult a licensed professional before choosing or switching a medication.