Plan B vs Propecia: side-by-side comparison
Plan B (Hormones and Birth Control) and Propecia (Male and Female Pattern Hair Loss) belong to different therapeutic classes and are rarely interchangeable. This page compares the medications' purposes, mechanisms and the situations where each is used.
| Property | Plan B | Propecia |
|---|---|---|
| Active ingredient | Levonorgestrel | Finasteride |
| Manufacturer | Foundation Consumer Healthcare | Merck |
| Class | Hormones and Birth Control | Male and Female Pattern Hair Loss |
| Strengths | 1.5mg | 1mg |
| Forms | tablet | tablet |
What's the same
Plan B and Propecia are used in very different patients, and the points in common are limited. The main shared element is that both meet regulatory standards for efficacy and safety and benefit from pharmacist oversight.
Key differences
Plan B belongs to Hormones and Birth Control while Propecia belongs to Male and Female Pattern Hair Loss. Indications, mechanisms and target populations differ. The comparison is most useful when a clinician has mentioned both medications and the patient wants to understand where each fits.
Mechanism and action
Plan B: Plan B's primary mechanism is delaying or preventing ovulation when taken before the LH surge. Propecia: DHT, produced from testosterone by 5-alpha-reductase, drives miniaturisation of scalp hair follicles in genetically susceptible men, gradually shortening anagen growth phases until follicles produce only fine vellus hair…
When Plan B is preferred
Plan B is indicated for emergency contraception after unprotected intercourse or known/suspected contraceptive failure, in women of reproductive age.
When Propecia is preferred
Propecia is approved for the treatment of male pattern hair loss (androgenetic alopecia) in men aged 18 to 41.
Frequently asked questions
Is Plan B or Propecia better? ▾
Plan B and Propecia are not interchangeable — they treat different conditions. Asking which is "better" is meaningful only when a clinician has weighed both for the same specific clinical scenario.
Can I switch from Plan B to Propecia? ▾
Switching between Plan B and Propecia is rarely an appropriate decision since they belong to different classes and treat different conditions. The real question is usually whether the diagnosis calls for one medication or the other — which the prescriber resolves.
Do Plan B and Propecia have the same side effects? ▾
No — they belong to different classes and have distinct side-effect profiles. Each medication has its own prescribing information.
More Plan B comparisons
The information on this website is provided for reference and educational purposes only. It does not replace consultation with a qualified healthcare professional.