Omeprazole (Losec)

Omeprazole (Losec) is a proton pump inhibitor that is used to reduce stomach acid levels. It is used to treat indigestion, stomach ulcers and acid reflux (heartburn). It can also be used to help eradicate the bacterium Helicobacter pylori, the major cause of ulcers in most patients. It works by preventing the secretion of acid into the stomach.

Omeprazole is produced in tablets and capsules, as well as a powder for solution and injection into a vein. It is available on prescription as a branded product, as well as a generic (non-brand name) product.

Omeprazole should not be taken by patients taking the protease inhibitor atazanavir (Reyataz), as this drug requires adequate levels of stomach acid to be absorbed. Studies in HIV-negative and –positive volunteers have shown that patients with reduced acid levels in the stomach have low levels of atazanavir in the blood, putting them at risk of treatment failure, with or without low-dose ritonavir (Norvir) boosting.1 2 However, two other studies have failed to replicate this finding in HIV-positive patients and an observational study did not find any evidence of impaired virological suppression in patients taking omeprazole, casting doubt on this interaction.3 4 5 Until further, larger studies are carried out, patients should avoid co-administering these drugs.

Similar interactions may exist with other protease inhibitors, including indinavir (Crixivan).6 Lopinavir may also interact in with omeprazole through the drugs’ similar routes of metabolism.7 8 Until more data are available, omeprazole should be used cautiously by patients taking these protease inhibitors.

There is no significant interaction between omeprazole and the protease inhibitors nelfinavir (Viracept), ritonavir or saquinavir (Invirase). It also does not interact with the non-nucleoside reverse transcriptase inhibitors (NNRTIs) efavirenz (Sustiva) and nevirapine (Viramune).


  1. Agarwala S et al. Pharmacokinetic (PK) effect of omeprazole (OMP) on atazanavir (ATV) with ritonavir (RTV) in healthy subjects. Twelfth Conference on Retroviruses and Opportunistic Infections, Boston, abstract 658, 2005
  2. Khanlou H et al. Co-administration of atazanavir with proton-pump inhibitors and H2 blockers. J Acquir Immune Defic Syndr 39: 503, 2005
  3. Furtek KJ et al. Proton pump inhibitor therapy in atazanavir-treated patients: contraindicated? J Acquir Immune Defic Syndr 41: 394-395, 2006
  4. Chan-Tack KM et al. Ritonavir-boosted atazanavir may be efficacious in HIV-infected patients concurrently receiving omeprazole. Clin Infect Dis 42: 1344, 2006
  5. Guiard-Schmid JB et al. Proton pump inhibitors do not reduce atazanavir concentrations in HIV-infected patients treated with ritonavir-boosted atazanavir. AIDS 19: 1937-1938, 2005
  6. Burger DM et al. Pharmacokinetic interaction between the proton pump inhibitor omepreazole and the HIV protease inhibitor indinavir. AIDS 12: 2080-2082, 1998
  7. Bertz RJ et al. Lack of effect of gastric acid reducing agents on lopinavir / ritonavir plasma concentrations in HIV-infected patients. Seventh International Congress on Drug Therapy in HIV Infection, Glasgow, abstract P279, 2004
  8. Yeh R et al. Lopinavir / ritonavir induces CYP2C9 and 2C19 activity as measured by warfarin and omeprazole biomarkers in healthy human volunteers. Fifth International Workshop on Clinical Pharmacology of HIV Therapy, Rome, abstract 4.1, 2004

Community Consensus Statement on Access to HIV Treatment and its Use for Prevention

Together, we can make it happen

We can end HIV soon if people have equal access to HIV drugs as treatment and as PrEP, and have free choice over whether to take them.

Launched today, the Community Consensus Statement is a basic set of principles aimed at making sure that happens.

The Community Consensus Statement is a joint initiative of AVAC, EATG, MSMGF, GNP+, HIV i-Base, the International HIV/AIDS Alliance, ITPC and NAM/aidsmap

This content was checked for accuracy at the time it was written. It may have been superseded by more recent developments. NAM recommends checking whether this is the most current information when making decisions that may affect your health.

NAM’s information is intended to support, rather than replace, consultation with a healthcare professional. Talk to your doctor or another member of your healthcare team for advice tailored to your situation.