Understanding What Is the Most Prescribed Biologic: Humira and the Evolving Landscape

October 9, 2025 •

4 min read

For years, the anti-inflammatory drug Humira (adalimumab) has been a dominant force in the pharmaceutical industry, recognized as the world's top-selling prescription medication. This widespread use has made it a historical contender for what is the most prescribed biologic, treating millions of people suffering from chronic inflammatory conditions such as rheumatoid arthritis, Crohn's disease, and psoriasis. However, the landscape of the biologic market is shifting dramatically with the introduction of numerous biosimilars and other innovative therapies.

Quick Summary

This article examines why Humira has been the most prescribed biologic for so long, detailing its mechanism and therapeutic applications. It also explores other key biologics on the market, the impact of biosimilars on cost and competition, and the future trends shaping biologic treatment.

Key Points

Humira (adalimumab) has been the historical market leader: Due to its efficacy and wide range of indications, Humira was once the world's top-selling drug and one of the most prescribed biologics.
Biologics are complex drugs from living organisms: Unlike chemically-made drugs, biologics are large, complex molecules, explaining their higher cost and typical injection/infusion administration.
The market includes other significant biologics: Alongside Humira, other widely used biologics include Remicade (infliximab), Enbrel (etanercept), and Stelara (ustekinumab), often targeting different inflammatory pathways.
Biosimilars are increasing competition and access: The entry of biosimilar versions of Humira and other biologics creates competition, which can lead to lower prices and better access for patients.
Market growth is driven by chronic disease prevalence: The rising number of people with chronic diseases like autoimmune disorders and cancer is fueling the growth and expansion of the global biologic market.
Biologics offer targeted therapy: Many biologics work by targeting specific immune system proteins, offering a more precise treatment approach than traditional, broadly acting medications.

What are Biologic Drugs?

Before delving into specific medications, it's important to understand what a biologic is. Unlike traditional small-molecule drugs that are chemically synthesized, biologic drugs are complex, large molecules produced from living organisms, such as human, animal, or microorganism cells. Due to their complex nature, they cannot be taken orally and are instead administered via injection or intravenous (IV) infusion.

Biologics are often used to treat autoimmune diseases and cancer by targeting specific proteins, cells, or pathways in the immune system to modify its response. This targeted approach can be more effective for complex diseases where traditional therapies have failed.

Humira: The Dominant Force

For nearly two decades, Humira (adalimumab) has held the position as the historically most prescribed biologic, a success driven by its efficacy and broad range of indications. It is a tumor necrosis factor (TNF) blocker, meaning it inhibits the action of TNF-alpha, a protein that causes inflammation in the body. By blocking TNF-alpha, Humira helps to reduce inflammation and manage symptoms across a wide variety of autoimmune conditions.

Key conditions Humira treats include:

Moderate to severe rheumatoid arthritis (RA)
Psoriatic arthritis (PsA)
Ankylosing spondylitis (AS)
Moderate to severe Crohn's disease (CD)
Moderate to severe ulcerative colitis (UC)
Moderate to severe hidradenitis suppurativa (HS)
Moderate to severe chronic plaque psoriasis (Ps)
Non-infectious uveitis

Humira is self-administered as an injection, typically once every two weeks, which has also contributed to its patient popularity. The drug's patent expiration in recent years has ushered in a new era of competition, introducing many biosimilar versions to the market.

Other Leading Biologics

While Humira may have long held the top spot, several other biologics have also achieved blockbuster status and are widely prescribed, offering alternatives for patients who may not respond to or tolerate adalimumab.

Remicade (infliximab): Another TNF-alpha blocker, Remicade is administered via IV infusion in a doctor's office. It is used for similar conditions to Humira, including RA, Crohn's disease, ulcerative colitis, and psoriatic arthritis.
Enbrel (etanercept): Also a TNF blocker, Enbrel is used to treat RA, PsA, and AS, and is administered as a subcutaneous injection, often weekly.
Stelara (ustekinumab): This biologic targets different inflammatory proteins (IL-12 and IL-23) and is used for conditions like plaque psoriasis, psoriatic arthritis, Crohn's disease, and ulcerative colitis.
Other notables: Keytruda (pembrolizumab) and Opdivo (nivolumab) are prominent biologics in the oncology field, while Dupixent (dupilumab) is widely used for conditions like atopic dermatitis and asthma.

The Rise of Biosimilars

The introduction of biosimilars is significantly impacting the biologic market. A biosimilar is a biological product that is highly similar to and has no clinically meaningful differences from an existing FDA-approved reference biologic. They are not generic drugs in the conventional sense due to the complexity of manufacturing biologics from living cells, meaning they cannot be exact replicas.

Market Impact: The arrival of numerous Humira biosimilars since 2023 promises to increase competition, potentially driving down costs and improving patient access to biologic therapy.
Cost and Access: Biologics are notoriously expensive, but biosimilars offer a more affordable option for many patients and healthcare systems. This is particularly impactful for patients who might otherwise struggle to afford treatment.

Comparison of Major Biologics


Feature	Humira (adalimumab)	Remicade (infliximab)	Enbrel (etanercept)
Mechanism	TNF-alpha blocker	TNF-alpha blocker	TNF-alpha blocker
Administration	Subcutaneous injection	Intravenous (IV) infusion	Subcutaneous injection
Frequency	Every 1 or 2 weeks	Starter doses, then every 8 weeks	Once or twice weekly
Key Conditions	RA, PsA, CD, UC, Ps	RA, PsA, CD, UC, Ps	RA, PsA, AS, JIA
Biosimilars	Multiple FDA-approved biosimilars available	Multiple biosimilars (e.g., Avsola, Inflectra) available	Several biosimilars available

Conclusion

While the answer to 'what is the most prescribed biologic?' has historically been Humira (adalimumab), the market is becoming increasingly dynamic. Humira's long-standing success is a testament to its broad utility for various inflammatory conditions. However, the introduction of biosimilars is fundamentally changing the market landscape, offering more affordable and accessible options for patients. This growing competition, coupled with the continued development of next-generation biologics like Stelara, is good news for patients, providing more choices for managing their chronic conditions. The future of the biologics market will likely be defined by a mix of established therapies, new innovative drugs, and increasingly popular biosimilar alternatives, all working to improve patient outcomes and affordability. For more information, consult the official FDA website.

Future Outlook

The biologic market is expected to continue its rapid growth, driven by an aging population and the rising prevalence of chronic autoimmune diseases and cancers. Advancements in biotechnology are leading to more targeted therapies and faster drug development timelines. The expansion of biosimilars will be a critical factor in managing healthcare costs and increasing global patient access. Additionally, research is progressing on new types of biologics, such as gene and cell therapies, which promise to revolutionize treatment for many diseases.

What This Means for Patients

For patients with chronic inflammatory diseases, the evolving biologic market offers both challenges and opportunities. While the cost of brand-name biologics remains high, the availability of biosimilars provides a more affordable pathway to treatment. It is crucial for patients to have open conversations with their healthcare providers about all available options, including the potential risks and benefits of different biologics and their biosimilar counterparts. Insurance coverage, potential side effects, and administration methods are all important considerations in choosing the right therapy. The increased competition may also spur innovation, leading to even more effective and safer treatments in the future.

Frequently Asked Questions

Traditional drugs are small, simple molecules created through chemical synthesis, often taken orally. In contrast, biologics are large, complex molecules derived from living organisms, requiring administration via injection or infusion.

Humira (adalimumab) is widely used to treat various autoimmune and inflammatory conditions, including rheumatoid arthritis, Crohn's disease, ulcerative colitis, psoriatic arthritis, ankylosing spondylitis, and plaque psoriasis.

A biosimilar is a biological product that is highly similar to an already FDA-approved reference biologic. It has no clinically meaningful differences in terms of safety, purity, and potency, but is not an exact duplicate.

Yes, biosimilars are generally more affordable than their reference biologics. Their introduction is expected to increase market competition and lower overall costs, improving patient access.

Because they are complex protein molecules that would be digested if taken orally, most biologics are administered through injections under the skin (subcutaneously) or via intravenous (IV) infusion.

Common side effects vary by drug but can include injection site reactions, upper respiratory infections, and headaches. More serious risks can include an increased risk of serious infections and certain types of cancer, as biologics can suppress the immune system.

Both Remicade and Humira are TNF-alpha blockers used for many of the same conditions. The primary difference is the administration method: Humira is a self-injected shot, while Remicade is administered as an IV infusion in a clinical setting.

While biosimilars are offering increasing competition, original biologics will remain on the market. Patient preference, clinical response, and insurance coverage can all influence whether an original biologic or a biosimilar is prescribed.