Nexium vs Prilosec vs Prevacid: which heartburn medicine is best?
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 | 70/100 | 70/100 | Not yet rated |
| Pharmacy pays | No data | ~$1.52 /30 | ~$5.10 /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.
Which should you choose?
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.
Frequently asked questions
Which PPI is the strongest for acid reflux?
At OTC doses the three control stomach acid to a broadly similar degree, and head-to-head differences are small for typical heartburn. The “best” is usually the one that relieves your symptoms at the lowest effective dose — often decided by price and your other medicines rather than potency.
How fast do they work?
Not instantly. PPIs reduce acid over 1–4 days as they reach full effect, so they're for frequent heartburn rather than sudden relief. For immediate relief, an antacid works faster.
Which has the fewest drug interactions?
Lansoprazole (Prevacid) generally interacts with fewer medicines than omeprazole (Prilosec) and esomeprazole (Nexium), which use the CYP2C19 enzyme and can affect drugs like clopidogrel. If you take other medicines, ask a pharmacist.
Are they safe to take long-term?
OTC PPIs are intended for short 14-day courses, up to three times a year. Long-term or frequent use can carry small risks and should be supervised by a doctor — don't self-treat indefinitely. General information, not medical advice.