Clarifying the Confusion: Why has fosfomycin been discontinued? (Spoiler: It hasn't fully)

October 14, 2025 •

3 min read

Despite a widespread misconception, the antibiotic fosfomycin has not been fully discontinued; instead, its brand-name version, Monurol, was pulled from the U.S. market, creating confusion. This led to questions like, 'Why has fosfomycin been discontinued?' but in reality, the drug is still widely used and available, particularly in generic forms.

Quick Summary

The antibiotic fosfomycin is still available, but its status is complex. While the brand-name version Monurol was discontinued, generic alternatives exist. Past regulatory restrictions in Europe affected specific uses, and manufacturing recalls have occurred. However, rising antimicrobial resistance keeps it relevant for treating infections, especially UTIs, making it a critical, though sometimes inconsistently supplied, therapeutic option.

Key Points

Brand Name vs. Generic: The original brand-name version, Monurol, was discontinued in the U.S., but generic versions of fosfomycin remain widely available.
Regulatory Restrictions: The European Medicines Agency (EMA) has restricted intravenous use to serious infections and suspended intramuscular and pediatric formulations due to safety and efficacy concerns, not a complete discontinuation.
Supply Chain Issues: Periodic shortages and manufacturing recalls have temporarily affected the availability of specific lots but do not represent a permanent withdrawal of the drug.
Continued Medical Relevance: Fosfomycin remains an important antibiotic, particularly for treating uncomplicated UTIs and infections caused by multidrug-resistant pathogens.
Effective Alternative: It is often prescribed when alternatives like nitrofurantoin are not suitable, especially for managing resistant bacteria like ESBL-E. coli.
Market Growth: Market analysis forecasts continued growth for fosfomycin, driven by the global increase in antibiotic resistance and its expanded clinical applications.

Discontinuation vs. Rebranding: The Monurol Confusion

One of the main reasons for the confusion regarding the availability of fosfomycin stems from the discontinuation of its original brand-name version, Monurol (manufactured by Zambon SPA), in the United States. After Zambon discontinued Monurol, generic versions were introduced to the market by other companies. For instance, Xiromed LLC launched the first AA-rated generic version of fosfomycin tromethamine in October 2020, ensuring the drug remained available for patients. However, in some regions, the original branded product's withdrawal created the perception that the drug itself was no longer an option. This is a crucial distinction: the brand disappeared, but the active ingredient and its generic equivalents remain accessible, albeit with potential differences in cost and specific formulation availability across different markets.

Regulatory Actions and Geographic Restrictions

Beyond brand discontinuation, international regulatory bodies have played a role in shaping how and where fosfomycin is used, which can contribute to the belief that it has been discontinued. In March 2020, the European Medicines Agency (EMA) issued recommendations to restrict the use of fosfomycin antibiotics. The EMA's review led to several significant changes:

Intravenous (IV) fosfomycin: Its use was restricted to treating serious infections (e.g., affecting the heart, lungs, blood) when other options are unsuitable.
Intramuscular (IM) fosfomycin: These products were suspended due to insufficient evidence of efficacy.
Pediatric granules (2g): The formulation for children was also suspended and removed from the market.
Oral granules (3g): Continued approval was maintained for uncomplicated cystitis in women and adolescent girls, as well as for prophylaxis during transrectal prostate biopsy in men.

These targeted suspensions and restrictions in Europe do not equate to a global discontinuation but highlight the nuanced regulatory landscape of the drug. The fact that certain formulations were deemed insufficiently effective or unsafe for specific populations led to their removal in some regions, further feeding the narrative of a broader withdrawal.

Manufacturing Recalls and Supply Chain Disruptions

As with many older antibiotics, fosfomycin has faced various manufacturing and supply chain challenges over the years. In February 2024, Ascend Laboratories recalled thousands of single-dose sachets of fosfomycin tromethamine in the U.S. due to samples testing out-of-specification for organic impurities. While this was a significant recall for a specific manufacturer's lots, it was not a market-wide discontinuation. Similar periodic shortages or production issues can cause temporary unavailability, which might be interpreted by some as a permanent discontinuation. For example, France experienced a temporary production crisis and shortage as far back as 2008, affecting distribution.

Importance of Fosfomycin in Combating Resistance

Despite the challenges, fosfomycin remains an important tool in the fight against antimicrobial resistance. The rise of multidrug-resistant (MDR) pathogens, including ESBL-producing E. coli which commonly cause UTIs, has renewed clinical interest in older antibiotics like fosfomycin. Its unique mechanism of action, which involves inhibiting bacterial cell wall synthesis at an early stage, prevents cross-resistance with other commonly used antibiotics. This makes it a valuable alternative for treating infections caused by resistant bacteria. Market reports even project growth in the global fosfomycin market, driven by the increasing need for effective antibiotics against resistant pathogens.

Comparison of Fosfomycin and Nitrofurantoin

To understand fosfomycin's continued role, it is useful to compare it with another common antibiotic for UTIs, nitrofurantoin.


Feature	Fosfomycin	Nitrofurantoin
Mechanism of Action	Inhibits bacterial cell wall synthesis, unique from other classes.	Multiple mechanisms, including protein synthesis inhibition.
Standard Dosing	Single oral dose (3g granules) for uncomplicated UTIs in women.	Multiple doses, typically twice a day for several days.
Effectiveness for Resistant Bacteria	Effective against many multidrug-resistant strains like ESBL-producing E. coli.	Less effective against some resistant strains compared to fosfomycin.
FDA-Approved Indication (USA)	Uncomplicated UTIs in women.	Treatment and prevention of UTIs.
Adverse Effects	Diarrhea, nausea, headache, vaginal candidiasis are common.	Nausea, headache, gas, potential for serious pulmonary and hepatic toxicity with long-term use.
Cost	Can be more expensive than some alternatives, even in generic form.	Generally less expensive, especially with generic versions.

Conclusion: The Persistence of a Valuable Drug

The perception that fosfomycin has been discontinued is largely a result of specific brand-name discontinuation, regulatory restrictions on certain formulations, and occasional supply chain issues, rather than a definitive market withdrawal. The drug remains a viable and often necessary treatment, particularly for uncomplicated UTIs and against multidrug-resistant pathogens. Healthcare providers continue to prescribe generic versions, and global market trends indicate its ongoing importance. The antibiotic landscape is dynamic, and fosfomycin's continued presence, despite its challenges, proves its enduring value in modern medicine.

Visit a resource for understanding fosfomycin's pharmacology

Frequently Asked Questions

Yes, fosfomycin is still available in the U.S. While the original brand-name version, Monurol, was discontinued, several companies now produce and sell generic equivalents.

The manufacturer of Monurol, Zambon SPA, discontinued the specific branded formulation. This is a business decision and is distinct from the regulatory status of the active ingredient, fosfomycin, which is now available from multiple generic manufacturers.

In Europe, the European Medicines Agency (EMA) suspended the use of intramuscular fosfomycin and the pediatric 2g granule formulation due to insufficient evidence supporting their efficacy.

While the drug is generally available, specific manufacturers or regions may experience temporary shortages or recalls. For example, a recall for organic impurities occurred in February 2024 for specific lots from Ascend Laboratories. It's best to check with your pharmacist for the latest supply status.

Fosfomycin remains a valuable treatment because of its effectiveness against multidrug-resistant bacteria, including some that are resistant to other common antibiotics. Its unique mechanism of action makes it a critical tool in managing antibiotic resistance.

Common alternatives include nitrofurantoin (Macrobid), trimethoprim-sulfamethoxazole (Bactrim), and some cephalosporins. The best option depends on the specific bacteria causing the infection and the patient's individual health profile.

Oral fosfomycin is FDA-approved for uncomplicated urinary tract infections (UTIs) in women. It is not typically used for pyelonephritis (kidney infection) or other complicated UTIs. Its use for other indications is considered off-label.