Plan B with antacids and acid blockers

Antacids and acid-blocking medications (PPIs like omeprazole, H2 blockers like ranitidine or famotidine) are widely used and can subtly affect the absorption of medications taken alongside them. For Plan B (Levonorgestrel) at 1.5mg, the impact depends on how Levonorgestrel is absorbed and whether gastric pH plays a role.

How antacids affect Plan B

Antacids work locally to neutralise gastric acid; PPIs and H2 blockers reduce acid secretion over hours. Some medications need an acidic stomach for proper dissolution and absorption — for these, co-administration with PPIs reduces effective dose. Other medications absorb fine regardless of pH. Whether Levonorgestrel is pH-sensitive is in the prescribing information. Plan B's primary mechanism is delaying or preventing ovulation when taken before the LH surge.

Practical guidance

According to general pharmacy practice, separating antacid doses from Plan B by 2 hours avoids most direct binding interactions. PPIs and H2 blockers, taken on their own schedule, do not need timing separation but can shift Levonorgestrel absorption over weeks of co-use. The pharmacist confirms whether Plan B at 1.5mg is affected.

Frequently asked questions

Can I take antacids with Plan B? ▾

Yes for most users, but separating the doses by 2 hours minimises any direct interaction with Levonorgestrel at 1.5mg. Some medications bind to antacid components and absorb less effectively if taken simultaneously.

Will my PPI affect Plan B? ▾

For most Hormones and Birth Control medications, no clinically meaningful interaction. For pH-sensitive active ingredients, chronic PPI use can reduce absorption of Plan B; the prescriber may consider an alternative or a dose adjustment if this applies to Levonorgestrel.

More on Plan B

The information on this website is provided for reference and educational purposes only. It does not replace consultation with a qualified healthcare professional.