Biologics are transforming modern medicine. Unlike traditional medications, such as pain relievers and antibiotics, which are made through chemical processes, biologic drugs are derived from living cells and designed to target specific disease pathways.

These advanced therapies are now used to treat cancer, autoimmune diseases, severe asthma, genetic disorders, and other complex conditions that were once difficult, or even impossible, to manage.

As biologic therapy becomes more common, patients are also hearing about biosimilars, costs, and potential side effects. This guide explains how biologics work, what conditions they treat, their risks, and how biosimilars help lower costs.

In contrast, biologic medications come from living cells and organisms, including humans, animals, and microorganisms. They consist of proteins, sugars, genes, cells, tissues, and other natural materials.

As a result, biologics have a more complex structure than synthetic drugs, and the exact composition of many biologics is unknown.

This guide explores how biologics work, the conditions they treat, their benefits and risks, and how biosimilars can improve access to these life-changing therapies.

What Is A Biologic?

Biological products, also called biologics, are made from living cells and organisms, including humans, animals, and microorganisms, such as donated blood, bone marrow, or other living tissues.

They include products such as vaccines, blood products, tissues, nucleic acids, stem cells, and gene therapy. This rapidly growing class of advanced medications is used to treat a wide range of medical conditions, including previously untreatable conditions such as cancers, blood disorders, autoimmune diseases, and genetic conditions.

How Are Biologics Made?

Biologics are made using biotechnology. Scientists use advanced techniques like cloning genes or implanting DNA in living cells to make biologic products. Most biologics are used to treat diseases that conventional drugs cannot treat. But biologic products are more complex and difficult to produce compared to traditional medications.

How Do Biologic Drugs Work?

Target Immune System Therapy

Biologics work by mimicking substances naturally found in the body. They precisely target specific parts of the body’s immune system. For example:

Blocking inflammatory proteins that cause joint or tissue damage.
Preventing inflammatory cells (T-cells, B-cells) from activating or reaching target tissues.
Blocking receptors on cells where inflammatory molecules bind.

Reducing Inflammation and Disease Activity

Biologics interrupt the inflammatory pathway that plays a key role in conditions such as ankylosing spondylitis, rheumatoid arthritis, psoriasis, and inflammatory bowel disease, thereby calming an overactive immune system and modifying disease activity.

Unlike traditional immunosuppressants, biologics target very specific pathways in the body. Biologics are designed to target molecules without suppressing the entire system. As a result, while biologics still carry safety risks, they may reduce certain systemic (body-wide) side effects compared with non-specific treatments.

Conditions Treated By Biologics

The United States Food and Drug Administration (FDA) has approved various biologic drugs, many of which are life-saving products for rare or previously untreatable conditions. A few examples of conditions treated with biological medications are listed below.

Autoimmune Diseases

Many biologics that are used to treat autoimmune disorders are monoclonal antibodies. They bind to specific components of the immune system, preventing them from attacking healthy tissue.

In 1998, the FDA approved infliximab (Remicade), one of the first monoclonal antibody biologics approved to treat Crohn’s disease.

Since then, many biologics have been approved to treat other autoimmune conditions, such as:

Rheumatoid arthritis
Plaque psoriasis
Psoriatic arthritis
Ankylosing spondylitis
Lupus
Inflammatory bowel disease (Crohn’s disease, ulcerative colitis)
Multiple sclerosis

Moderate to Severe Asthma & Atopic Dermatitis (Eczema)

When inhalers and traditional medications fail to control symptoms, healthcare providers may recommend add-on biologic therapy. Many biologics used to treat asthma are antibodies (proteins that bind to and block specific molecules that trigger airway inflammation).

Examples of FDA-approved biological medications used in asthma treatment include:

Mepolizumab (Nucala)
Reslizumab (Cinqair)
Benralizumab (Fasenra)
Dupilumab (Dupixent)
Omalizumab (Xolair)
Tezepelumab-ekko (Tezspire)

In addition to asthma, dupilumab (Dupixent) is also FDA-approved for the treatment of moderate to severe atopic dermatitis (eczema), a chronic inflammatory skin disease that is not controlled with topical treatments.

Cancers

Biological drugs for cancer treatment help the body's immune system recognize and kill cancer cells. Some biologics block proteins in cancer cells to stop their growth.

Examples of biological medications and some of their approved treatments include:

Bevacizumab (Avastin): Colorectal cancer, non-small cell lung cancer, renal cell cancer
Rituximab (Rituxan): Non-Hodgkin’s lymphoma
Trastuzumab (Herceptin): Breast cancer, gastric cancer
Pertuzumab (Perjeta): Breast cancer
Denosumab (Xgeva): Multiple myeloma

Biologics are now used to treat many kinds of cancer, such as melanoma, lung cancer, kidney cancer, head and neck cancers, Hodgkin’s lymphoma, blood cancers, urinary tract cancers, colorectal cancer, liver cancer, breast cancer, cervical cancer, and stomach cancer.

Why Are Biologics Given as Injections or Infusions?

Large and Delicate Molecules

Biologics are complex medicines that consist of large protein molecules, which are 200 to 1000 times the size of small-molecule drugs (chemical drugs that are mainly available in oral dosage forms).

The large molecules of biological medicines cannot be effectively absorbed from the gut into the bloodstream. Additionally, the acidic environment of the stomach and digestive enzymes in the intestines can break down the protein structure of a biologic medicine, making it inactive and ineffective before it is absorbed into the bloodstream.

For these reasons, biologics need to be directly administered into the bloodstream through injections or infusions. These methods allow the drug to remain intact and reach the target site.

Subcutaneous Injections vs IV Infusions

The method of injection depends on the specific drug, the required dosage, and how quickly the medication needs to work.

Subcutaneous (SC) injections are placed in the fatty layer just beneath the skin surface. This method is used for smaller volumes of medicines or if a medicine requires slow, more sustained absorption into the bloodstream.
Intravenous (IV) infusion is delivered directly into a vein over a period of several minutes to hours. It is used for large volumes of medicines or when a medicine is required to reach the bloodstream and target tissues immediately.

Self-Injection Devices (Pens, Syringes)

Many biologics used to treat chronic inflammatory conditions are available as user-friendly self-injection devices that allow patients to manage their treatment at home. These devices include:

Single-use syringes pre-filled with the exact dose of medication, reducing preparation steps and potential dosage errors.
Auto-injector pens with a spring-loaded mechanism that automatically insert the needle and inject the medication when pressed against the skin, making the process simpler and less intimidating for patients.

Self-injection devices improve convenience and adherence for autoimmune conditions such as rheumatoid arthritis, psoriasis, and inflammatory bowel disease, where long-term, regular dosing of biological medications is necessary.

Common Types of Biologic Drugs

More than 600 biologics are available in the US. The drug class, brand names, and active ingredients of some biologics examples are listed below.

Tumor Necrosis Factor (TNF) Inhibitors

Adalimumab (Humira)
Certolizumab pegol (Cimzia)
Etanercept (Enbrel)
Golimumab (Simponi)
Infliximab (Remicade)

Interleukin Inhibitors

Benralizumab (Fasenra)
Brodalumab (Siliq)
Dupilumab (Dupixent)
Guselkumab (Tremfya)
Ixekizumab (Taltz)
Mepolizumab (Nucala)
Risankizumab-rzaa (Skyrizi)
Secukinumab (Cosentyx)
Ustekinumab (Stelara)

B-Cell Inhibitors

Belimumab (Benlysta)
Ofatumumab (Kesimpta)
Ocrelizumab (Ocrevus)
Rituximab (Rituxan)

T-Cell Inhibitors

Abatacept (Orencia)
Ipilimumab (Yervoy)

What Is A Biosimilar?

A More Affordable Alternative to Brand-Name Biologics

A biosimilar is a medication that is highly similar to an existing FDA-approved biologic drug (called the reference product). Because biologics are made from living cells, they cannot be copied exactly as traditional generic drugs are. Instead, biosimilars are developed to closely match the original biologic in structure, function, and clinical performance.

Biosimilars are introduced after the reference biologic’s exclusivity period ends and are typically offered at a lower cost, helping improve access to biologic therapy.

Safety, Effectiveness, and FDA Standards

The U.S. Food and Drug Administration (FDA) requires biosimilars to meet rigorous standards for safety, effectiveness, purity, and manufacturing quality.

To gain approval, manufacturers must demonstrate that there are no clinically meaningful differences between the biosimilar and the reference biologic in terms of treatment outcomes or safety risks.

Patients can expect the same therapeutic benefits and similar side effect profiles as the original biologic.

A Lower-Cost Alternative to Biologic Drugs

The primary difference is cost. Biosimilars are generally more affordable, which can reduce out-of-pocket expenses and expand access to life-saving treatments.

Benefits of Biologics

Effective When Other Treatments Fail

Biologics are a major breakthrough for severe cases of many diseases where conventional drugs don't work, providing new hope and better outcomes for patients.

For example, biological drugs can be used in patients with severe rheumatoid arthritis when symptoms are not controlled with other treatments like NSAIDs, steroids, and older disease-modifying antirheumatic drugs.

Targeted Treatment

Instead of broadly suppressing the immune system like chemical drugs, biologics block specific molecules (like TNF-alpha, IL-6) that cause inflammation. As a result, a biologic medicine generally causes fewer systemic (body-wide) side effects.

Improved Quality Of Life

By reducing pain, swelling, inflammation, and tissue damage, biologics can significantly improve function and overall well-being. Treatment with biological medicines often leads to a more stable disease course and better long-term prognosis.

Risks and Side Effects of Biologic Injections

Increased Infection Risk

Biologic drugs suppress specific parts of the immune system by blocking immune cells like T-cells or B-cells. Treatment with these drugs can therefore increase the risk of infections or reactivate dormant infections.

Injection Site Reactions

Injection site reactions (pain, redness, swelling) are common side effects. These side effects are temporary, and a cold compress can help to reduce discomfort.

Rare But Serious Reactions

In a small number of people, biologic drugs can cause serious side effects, such as allergic reactions or malignancies (for example, an increased risk of lymphoma).

Patients should always discuss risks and monitoring requirements with their healthcare provider.

Biologics Cost and Insurance Considerations

Why Are Biologics Expensive?

Biologics are complex molecules produced by advanced biotechnology processes from living cells. They require significant research and development (R&D), leading to high costs.

Insurance Barriers

Insurance coverage can lower the out-of-pocket cost of biologics. But most biologics require prior authorization and step therapy (documentation that lower-cost first-line treatments have been tried and have not helped).

Financial Assistance

Many manufacturers of biological products offer copay assistance or patient assistance programs to help reduce patients' out-of-pocket expenses. But many patients still face high costs. Interchangeable biosimilars, when available, have only slight variations from the originals and offer a more affordable treatment option.

FAQ Section

Are Biologics Considered Immunosuppressants?

Biologics are considered immunomodulators rather than immunosuppressants because they modulate the immune system by targeting specific pathways rather than broadly suppressing the entire system, as traditional drugs do.

How Long Does It Take For A Biologic To Start Working?

Biologics don’t start working immediately. According to the Arthritis Foundation, when treating rheumatoid arthritis, it can take 2-12 weeks to see initial improvement in symptoms after you start treatment. The full effects of the medicine can take 3-6 months.

Do Biologics Cure Autoimmune Diseases?

No, biologics don't cure autoimmune diseases. They help to control inflammation, manage symptoms, and slow disease progression by targeting specific components of the body’s immune response. Biologics can therefore significantly improve the quality of life for many patients, but the underlying autoimmune condition is not cured and requires ongoing management.

Can I Stop Or Restart A Biologic After A Flare?

Do not stop or restart a biologic after a flare without first consulting your healthcare provider. Stopping the medication on your own can lead to worsening symptoms. Stopping and starting biologics can make them less effective.

Are All Biologics Expensive?

Yes, most biologics are expensive because they are complex mixtures of molecules obtained from living organisms. Other factors that affect the cost of biologics are research and development, administration by injection or infusion, high demand, and limited competition. Biosimilars are lower-cost alternatives that help in increasing access to these therapies.