The World Health Organization (WHO) maintains a Model List of Essential Medicines, a catalog of drugs considered necessary to meet the most important health needs of any population. Now in its 24th edition, updated in September 2025, the list serves as a guide for countries building their own national drug supply systems. About 137 of 194 WHO member states (roughly 71%) have developed formal national essential medicines lists based on this model.
What Makes a Medicine “Essential”
The WHO defines essential medicines as those that satisfy the priority health care needs of a population. That definition is deliberately broad. A medicine doesn’t need to be the newest or most advanced option available. It needs to meet three core criteria: the disease it treats must be prevalent and relevant to public health, there must be solid evidence that the drug is effective and safe, and it must offer reasonable value compared to alternatives.
This means the list isn’t simply a ranking of the best drugs in the world. It’s a practical tool designed so that even countries with limited budgets can identify a baseline set of treatments their health systems should stock and provide. A country with high rates of tuberculosis, for instance, will find the antibiotics it needs on the list alongside cancer treatments, pain relievers, vaccines, and dozens of other categories.
How the List Gets Updated
A WHO Expert Committee meets every two years to review applications for adding, changing, or removing medicines. Committee members are drawn from WHO Expert Advisory Panels and are selected for their professional expertise, with an emphasis on geographic and gender balance so that practical experience from all income levels and regions is represented.
Anyone can submit an application requesting a change to the list, including researchers, pharmaceutical companies, governments, and nonprofit organizations. The committee evaluates each application against the same criteria of disease relevance, efficacy, safety, and cost-effectiveness. When a drug is added, it signals to health systems worldwide that the evidence supports making it widely available.
The 2025 Update
The most recent revision, published in September 2025, added 20 new medicines to the adult list and 15 to the children’s list, along with expanded uses for seven drugs already included. Two categories of additions stand out.
For cancer, the committee added pembrolizumab as a first-line treatment for metastatic cervical cancer, metastatic colorectal cancer, and metastatic non-small cell lung cancer. Atezolizumab and cemiplimab were included as alternatives for lung cancer. These are immunotherapy drugs that help the immune system recognize and attack cancer cells, and their inclusion on the list is a significant step toward broadening access in lower-income countries where such treatments have been largely unavailable.
For type 2 diabetes and obesity, the committee added a class of drugs called GLP-1 receptor agonists, including semaglutide, dulaglutide, and liraglutide, plus tirzepatide (a dual-action drug targeting two hormonal pathways). These were listed specifically for adults with type 2 diabetes who also have established cardiovascular disease, chronic kidney disease, or obesity with a BMI of 30 or higher. Their addition reflects growing evidence that these drugs reduce serious cardiovascular complications, not just blood sugar levels.
A Separate List for Children
The WHO publishes a companion Essential Medicines List for Children, now in its 10th edition. Children aren’t small adults: they metabolize drugs differently, often can’t swallow tablets, and need formulations designed for their size and development. The children’s list identifies medicines with appropriate dosage forms, such as dispersible tablets, oral liquids, and pediatric-strength injections, so that countries can ensure their youngest patients aren’t treated with improvised fractions of adult medications.
How Listing Affects Drug Access and Pricing
Being named an essential medicine doesn’t automatically make a drug cheaper or more available. There is no established causal link between a medicine appearing on the WHO list and a subsequent drop in its price. In many low- and middle-income countries, prices can actually be higher than in wealthier nations because governments lack the purchasing power or regulatory mechanisms to negotiate lower costs.
What the list does provide is political and legal leverage. When WHO designates a medicine as essential, it strengthens the case for governments to issue compulsory licenses, which allow local manufacturers to produce generic versions of patented drugs. It also creates symbolic momentum: when direct oral anticoagulants were added to the list, researchers from lower-income countries noted that the designation pushed their governments to prioritize availability of those drugs, even before prices dropped.
The real price reductions tend to come from related WHO mechanisms working in concert with the list. The WHO Prequalification Program certifies that generic medicines meet international quality, safety, and efficacy standards. Once prequalified, those generics become eligible for pooled procurement, where large buyers like the Global Fund and PEPFAR purchase in bulk. This combination has produced dramatic results: coordinated efforts between WHO guidelines, prequalification, and pooled procurement drove prices of commonly used HIV antiretroviral regimens down by more than 80% between 2004 and 2008. Regional bodies like the Pan American Health Organization’s Strategic Fund use a similar model, giving countries access to quality-assured medicines at lower prices and offering interest-free credit to bridge procurement gaps.
The Essential Diagnostics List
In 2018, WHO introduced a companion Model List of Essential In Vitro Diagnostics to address a gap: prescribing the right medicine requires first making the right diagnosis. The diagnostics list links specific tests to the treatments on the essential medicines list, aiming to ensure that health facilities can identify conditions before treating them. The first edition contained 113 tests; subsequent updates in 2019 and 2020 added tests for noncommunicable diseases and pandemic pathogens like COVID-19.
The main barrier facing both lists is the same: poorly equipped health facilities. Stock-outs of medicines and laboratory reagents, inadequate infrastructure, and limited space for service delivery remain common obstacles, particularly in the settings where these lists are most needed. The lists define what should be available. Closing the gap between that standard and reality remains the harder problem.