Plan B vs Valtrex: side-by-side comparison
Plan B (Hormones and Birth Control) and Valtrex (Antiviral Medications) 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 | Valtrex |
|---|---|---|
| Active ingredient | Levonorgestrel | Valacyclovir |
| Manufacturer | Foundation Consumer Healthcare | GlaxoSmithKline |
| Class | Hormones and Birth Control | Antiviral Medications |
| Strengths | 1.5mg | 500mg, 1000mg |
| Forms | tablet | tablet |
What's the same
Plan B and Valtrex 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 Valtrex belongs to Antiviral Medications. 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. Valtrex: Valacyclovir is rapidly and almost completely converted to acyclovir during first-pass intestinal and hepatic metabolism by valacyclovir hydrolase.
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 Valtrex is preferred
Valtrex is approved in adults for the treatment of herpes simplex virus infections, including genital herpes (initial episodes, recurrent episodes and suppressive therapy), herpes labialis (single-day high-dose regimen), reduction of transmission in heterosexual immunocompetent a…
Frequently asked questions
Is Plan B or Valtrex better? ▾
Plan B and Valtrex 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 Valtrex? ▾
Switching between Plan B and Valtrex 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 Valtrex 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.