Nexium, Prilosec and Prevacid are proton-pump inhibitors (PPIs) — they lower stomach-acid production to treat frequent heartburn and acid reflux. All three are available over the counter (as 14-day courses) and as low-cost generics, and they work in the same way, so differences are modest.
For frequent heartburn the three are broadly comparable and largely interchangeable. PPIs aren't for instant relief — they take a few days to reach full effect, so they're for frequent (2+ days a week) heartburn, not a one-off. The main practical differences are price/availability and drug interactions: omeprazole (Prilosec) and esomeprazole (Nexium) interact with more medicines than lansoprazole (Prevacid).
| Nexium esomeprazole | Prilosec omeprazole | Prevacid lansoprazole | |
|---|---|---|---|
| Active ingredient | Esomeprazole Magnesium | Omeprazole | Lansoprazole |
| Our rating | Not yet rated | Not yet rated | Not yet rated |
| Typical price | — | ~$1.52 /30 | ~$5.20 /30 |
| Time to full effect | 1–4 days | 1–4 days | 1–4 days |
| Drug interactions | More (shares omeprazole's enzyme pathway) | More (CYP2C19) — e.g. can affect clopidogrel | Fewer than omeprazole/esomeprazole |
| Best taken | Morning, before eating | Morning, before eating | Morning, before eating |
| Good to know | The S-isomer of omeprazole; works essentially the same way. Available OTC as Nexium 24HR. | The original OTC PPI — effective and low-cost. Available OTC as Prilosec OTC. | Comparable acid control with fewer of the omeprazole/esomeprazole interactions. OTC as Prevacid 24HR. |
Ratings are our independent FDA recall-safety score. General information, not medical advice.
Nexium (esomeprazole)
The S-isomer of omeprazole; works essentially the same way. Available OTC as Nexium 24HR.
Prilosec (omeprazole)
The original OTC PPI — effective and low-cost. Available OTC as Prilosec OTC.
Prevacid (lansoprazole)
Comparable acid control with fewer of the omeprazole/esomeprazole interactions. OTC as Prevacid 24HR.
These three control acid similarly; choose mostly on price, availability and your other medicines. Take a PPI in the morning before eating, and remember it can take 1–4 days to work fully — for instant relief an antacid is faster. Per the label, OTC PPIs are meant for a 14-day course up to three times a year; longer or recurring use should be guided by a doctor, who can also weigh the small risks linked to long-term use. If you take clopidogrel or other interacting drugs, lansoprazole (Prevacid) may interact less than omeprazole/esomeprazole — ask a pharmacist. Seek care for alarm symptoms (trouble swallowing, vomiting, weight loss, black stools). General information, not medical advice.