What is the most expensive antibiotic and why new antibiotics are costly?

October 8, 2025 •

4 min read

According to a BMJ Medicine study, some of the most expensive new antibiotics show ambiguous evidence of added benefit yet carry significant costs. Determining what is the most expensive antibiotic can be complex, as costs vary dramatically based on location, treatment course length, and the specific pathogen being targeted. Several factors contribute to the high price tag of these powerful, and often last-resort, medications, including the immense research and development costs required to combat rising antimicrobial resistance.

Quick Summary

Identifying the single most expensive antibiotic is challenging due to variable pricing, but novel intravenous agents used for resistant bacteria are among the costliest. High prices are driven by complex research and development, limited patient populations for niche drugs, and the market pressures of fighting antimicrobial resistance. Cost is also impacted by whether a drug is a brand-name or generic formulation.

Key Points

High-End Antibiotics are Newer and Intravenous: The most expensive antibiotics are typically newer, brand-name, and administered intravenously for serious, often hospital-acquired, infections involving multidrug-resistant bacteria.
No Single Most Expensive Drug: It's difficult to name one single "most expensive" antibiotic because the cost depends on the dosage, length of treatment, and location, with pricing for innovative agents being highly variable.
R&D and Market Forces Drive High Prices: The immense cost of research and development for new antibiotics, the limited market size for these last-resort drugs, and a lack of competition all contribute to their high price tags.
Resistance Increases Cost: The global rise in antimicrobial resistance necessitates the development of newer, more effective antibiotics, which inherently increases costs compared to older, generic drugs.
Last-Resort Drugs are Costly: Drugs like ceftolozane/tazobactam and meropenem/vaborbactam are examples of expensive combination therapies used when older treatments fail, reflecting their value in the face of resistant pathogens.
Generic Options are Much Cheaper: Common infections can often be treated effectively with significantly more affordable generic antibiotics, which can be 80-90% less expensive than their brand-name counterparts.

What Defines an 'Expensive' Antibiotic?

Pinpointing a single most expensive antibiotic is difficult because the cost can be measured in different ways—per dose, per course of treatment, or per year. For instance, a single-dose treatment could have an incredibly high price, while a longer course of a different drug might accumulate a higher total cost over time. The most expensive antibiotics tend to be newer, brand-name, intravenous formulations used in hospital settings to treat multidrug-resistant (MDR) or extensively drug-resistant (XDR) bacterial infections. These are often last-resort options for serious infections that have failed to respond to other treatments.

High-Cost Antibiotic Examples

While not the most expensive medication overall, which can run into millions of dollars for gene therapies, some antibiotics and their combinations carry extremely high costs. Examples of such medications include:

Ceftolozane/tazobactam (Zerbaxa): This combination is an intravenous antibiotic used for complicated intra-abdominal infections and complicated urinary tract infections. While not reaching the million-dollar price tag of some rare disease drugs, it is priced significantly higher than older, more common antibiotics.
Meropenem/vaborbactam (Vabomere): As a newer combination antibiotic, it is used to treat complicated urinary tract infections and pyelonephritis. As with other novel agents, it commands a premium price due to its efficacy against resistant bacteria.
Pretomanid: This antibiotic is used in combination with bedaquiline and linezolid for certain forms of highly resistant tuberculosis. A single course of treatment was estimated at $36,399 in a 2022 study.
Carbapenems (like Meropenem): Older studies have identified carbapenems as one of the most expensive classes of antibiotics, particularly in intensive care units, due to their broad spectrum of activity and need for intravenous administration for severe infections.

The Economics of Antimicrobial Resistance

The battle against antimicrobial resistance (AMR) is a primary driver of the high cost of new antibiotics. As bacteria evolve and develop resistance, pharmaceutical companies must invest vast resources into developing new drugs that can overcome these mechanisms. However, the development pipeline is notoriously sparse, leading to a shortage of truly innovative antibiotics.

Here’s how the economics play out:

High Research and Development (R&D) Costs: Developing a new antibiotic is a costly and lengthy process. The cost of bringing a drug to market can exceed $1 billion. Unlike drugs for chronic conditions, a new antibiotic may be used sparingly to preserve its effectiveness, meaning sales volumes are lower, and the R&D costs must be recouped from a smaller number of prescriptions.
Limited Market: To prevent resistance, new antibiotics are reserved for patients with severe infections caused by resistant bacteria. This limits the market size, which in turn reduces the potential revenue for the manufacturer.
Short Treatment Duration: Most antibiotics are used for a short course of treatment, unlike drugs for chronic diseases that patients take for years. This further decreases the total revenue generated per patient.

Market and Pricing Factors

The final price of an antibiotic is influenced by several market forces and healthcare system dynamics:

Brand Name vs. Generic: Generic versions of older antibiotics are significantly cheaper, sometimes 80-90% less than their brand-name counterparts. However, for newly developed drugs, brand-name exclusivity means prices remain high until generics become available, often many years later.
Type of Infection: The specific type of infection also dictates the cost. Treating community-acquired infections often involves older, more affordable antibiotics, while nosocomial (hospital-acquired) and MDR infections require newer, more expensive agents.
Supply and Demand: Drug shortages, often caused by manufacturing issues, can lead to significant price increases. While many antibiotics are widely available, some specialty or last-resort drugs may have limited supply chains.

Understanding Antibiotic Costs: A Comparison Table

To illustrate the wide range of costs, the following table compares the approximate out-of-pocket costs for common generic antibiotics with some of the more expensive intravenous agents (prices can vary significantly).


Feature	Common Generic Antibiotics	Advanced Intravenous Antibiotics
Example Drugs	Amoxicillin, Azithromycin, Ciprofloxacin	Zerbaxa, Vabomere, Pretomanid
Targeted Bacteria	Broad range of common infections	Multidrug-resistant (MDR) bacteria
Typical Administration	Oral tablets/capsules (outpatient)	Intravenous infusion (inpatient/hospital)
Cost (per course)	~$10 - $40 without insurance	Hundreds to tens of thousands of dollars
Development	Long-standing, off-patent drugs	Recently developed, brand-name, innovative agents
Market	Wide usage, high volume	Niche, limited patient population to preserve efficacy

Conclusion

While a definitive answer to what is the most expensive antibiotic remains elusive due to the nuances of pricing and administration, the trend points towards newer, potent, and often last-resort intravenous medications. The high cost is an unavoidable consequence of the complex process of developing new drugs to combat rising antimicrobial resistance, with R&D costs, limited patient populations, and market exclusivity all playing a role. This reality highlights the ongoing challenge of balancing innovation with affordability in the healthcare system, especially in the context of a global public health threat like antimicrobial resistance.

Frequently Asked Questions

Newer antibiotics are typically more expensive because of the immense costs associated with their research and development, clinical trials, and manufacturing. Companies need to recoup these investments, especially since new drugs are often reserved for resistant infections, limiting their market size and potential revenue.

No. The choice of antibiotic depends on the type and severity of the infection, and its susceptibility to different drugs. A doctor will typically prescribe a less expensive, older-generation antibiotic first, and only use newer, more expensive ones if the infection is resistant or severe.

Generic antibiotics are significantly cheaper than brand-name versions, often costing 80-90% less. They contain the same active ingredients and are considered equally effective for treating infections.

As antibiotic resistance grows, it drives up the cost of treatment. This is because infections become harder to treat, sometimes requiring more expensive, powerful, and novel last-resort drugs. It also necessitates costly R&D for new drugs to combat these resistant strains.

You can find more affordable antibiotics by opting for generic versions whenever possible, comparing prices between different pharmacies, and utilizing discount programs or prescription coupons from websites like GoodRx or SingleCare. Discussing cost with your doctor can also help explore cheaper alternatives.

Zerbaxa and Vabomere are examples of high-cost intravenous combination antibiotics used for serious, resistant infections. While they are among the most expensive antibiotics available, pinpointing a single most expensive one is difficult due to varying treatment costs and market prices.

A 2022 study in BMJ Medicine found that some expensive, new antibiotics were approved based on limited data and did not always demonstrate superior effectiveness over existing, cheaper alternatives. This is sometimes a result of rushed development pipelines to address antimicrobial resistance.