HeartburnTwo labels compared
Pepcid AC vs Prilosec OTC
These two products sit next to each other on the same shelf and are not the same kind of medicine. The clearest way to see the difference is not the class name but the instructions: one label lets you take it in advance, the other does not.
Pepcid AC
- Ingredient
- Famotidine
- Approved for
- Relieving and preventing heartburncovers heartburn
- Supply
- Over the counter
- Boxed warning
- None
- Pharmacy cost
- not listedwhat pharmacies pay to buy it, not the price at the counter
Prilosec OTC
- Ingredient
- Omeprazole
- Approved for
- Frequent heartburn, as a 14-day coursecovers heartburn
- Supply
- Over the counter
- Boxed warning
- None
- Pharmacy cost
- $14.78 per tablet, capsule or pen, brandwhat pharmacies pay to buy it, not the price at the counter
Side by side, straight from the labels
Generated from the two source labels, not typed out by hand, so it cannot drift from what the regulator approved. Rows where both labels say exactly the same thing are marked.
| Label section | Pepcid ACFamotidine | Prilosec OTCOmeprazole |
|---|---|---|
| Active ingredient | Pepcid ACFamotidineHistamine-2 receptor antagonist | Prilosec OTCOmeprazoleProton pump inhibitor |
| Approved for | Pepcid ACRelieving and preventing heartburn | Prilosec OTCFrequent heartburn, as a 14-day course |
| Supplysame in both | Pepcid ACOver the counter | Prilosec OTCOver the counter |
| What pharmacies payAcquisition cost, not retail | Pepcid ACnot listed | Prilosec OTC$14.78 per tablet, capsule or pen, brand |
| Boxed warningsame in both | Pepcid ACNone | Prilosec OTCNone |
| What this product is for | Pepcid AC
| Prilosec OTC
|
| Active ingredient (in each tablet) | Pepcid AC
| Prilosec OTC
|
| Directions | Pepcid AC
| Prilosec OTC
|
| Stop use and ask a doctor if | Pepcid AC
| Prilosec OTC
|
| Warnings | Pepcid AC
| Prilosec OTC
|
| Do not use | Pepcid AC
| Prilosec OTC
|
| Label version | Pepcid AC6 February 2026 | Prilosec OTC1 October 2025 |
One prevents, the other treats a course
The Pepcid AC label covers two uses: relieving heartburn associated with acid indigestion and sour stomach, and preventing it when brought on by eating or drinking certain foods and beverages. For prevention it gives a window, one tablet at any time from 15 to 60 minutes before the food or drink in question, with no more than two tablets in 24 hours.
The Prilosec OTC label has no such option. It authorizes one tablet a day, every day, for 14 days, and states in its own words that the product is not intended for immediate relief of heartburn and may take 1 to 4 days for full effect.
Different classes, and the labels say so
Famotidine is a histamine-2 receptor antagonist. Its prescription label describes it as a competitive inhibitor of histamine-2 receptors whose primary clinically important activity is inhibition of gastric secretion, suppressing both the concentration and the volume of what the stomach produces.
Omeprazole is a proton pump inhibitor. The prescription omeprazole label places it among the substituted benzimidazoles, which suppress gastric acid secretion by specific inhibition of the enzyme system at the secretory surface of the gastric parietal cell.
Who each shop label covers
Pepcid AC is for adults and children 12 years and over, and directs that children under 12 ask a doctor. Prilosec OTC is for adults 18 years and older only.
Both are 14-day products in practice: each says to stop and ask a doctor if it is needed for more than 14 days. Only the proton pump inhibitor adds the further limit of no more than one course every four months.
Where the two labels agree completely
Both carry the same list of reasons to see a doctor rather than keep taking the product: heartburn lasting over three months, heartburn with lightheadedness, sweating or dizziness, chest or shoulder pain with shortness of breath or pain spreading to the arms, neck or shoulders, frequent chest pain, trouble or pain swallowing, vomiting with blood, bloody or black stools, unexplained weight loss, frequent wheezing with heartburn, nausea or vomiting.
The Pepcid AC label adds one instruction the other does not carry in the same form: do not use with other acid reducers.
Common questions
- Which one works faster?
- Neither label states an onset time in minutes, so this page cannot give one. What the labels do differ on is what they allow: Pepcid AC may be taken 15 to 60 minutes before food expected to cause heartburn, while Prilosec OTC states that it is not intended for immediate relief and may take 1 to 4 days for full effect.
- Can they be taken together?
- The Pepcid AC label says not to use it with other acid reducers. Anyone whose heartburn is not controlled by one product is directed by both labels to a doctor.
- Is famotidine the same as ranitidine?
- They belong to the same class of histamine-2 receptor antagonists, but they are different molecules with different labels, and this page is built only from the documents it links. Ranitidine products were withdrawn from the US market and are not covered here.
Sources
Every fact above comes from one of these documents. The date is the effective date of the label version this page was built from.
FDA prescribing information for Pepcid AC
Kenvue Brands LLC. Label version 20, effective 6 February 2026.
FDA prescribing information for Prilosec OTC
The Procter & Gamble Manufacturing Company. Label version 17, effective 1 October 2025.
Each stripe is one section of the label, each division in a stripe one entry in that section.
Other comparisons in this category
Page last updated 29 August 2026
Compiled by the HealthyStudy editorial team from FDA source documents. No medical reviewer is credited on this page, because none reviewed it.