Adverse Event Monitoring for Biosimilars: How Safety Surveillance Works in Real-World Use

When a patient gets a biosimilar instead of the original biologic drug, they shouldn’t have to worry about hidden risks. But unlike generic pills, biosimilars aren’t exact copies. They’re made from living cells, which means tiny differences in how they’re produced can affect how the body reacts. That’s why adverse event monitoring for biosimilars isn’t optional-it’s critical. Without it, rare but serious side effects could go unnoticed, patients could be put at risk, and trust in these cost-saving treatments could collapse.

Why Biosimilars Need Special Monitoring

Biosimilars are not like generic drugs. A generic aspirin is chemically identical to the brand-name version. But a biosimilar for rheumatoid arthritis, like Amjevita (adalimumab-atto), is only highly similar to its reference product, Humira. It’s made from living cells, not synthesized in a lab. Even small changes in the manufacturing process-temperature, fermentation time, purification steps-can alter the protein structure just enough to trigger an immune response. That’s called immunogenicity. And while most patients won’t react, some might develop antibodies that reduce effectiveness or cause dangerous inflammation.

That’s why regulators don’t treat biosimilars like generics. The FDA, EMA, and Health Canada all require extra safety steps after approval. These aren’t just paperwork. They’re real-time systems designed to catch signals that lab studies and clinical trials might miss. Clinical trials usually involve a few thousand patients over a few years. Real-world use involves millions. And in that scale, rare side effects-like severe allergic reactions or autoimmune disorders-can emerge.

How Adverse Events Are Reported

There are two main ways adverse events get tracked: spontaneous reporting and active surveillance.

Spontaneous reporting relies on doctors, pharmacists, and patients to report side effects. In the U.S., this happens through the FDA’s FAERS system. In Europe, it’s EudraVigilance. These systems collect hundreds of thousands of reports every year. But here’s the problem: if a patient gets a biosimilar and has a reaction, but the doctor doesn’t write down the exact product name, the report gets lost in the noise. A 2022 survey found that 63.4% of U.S. physicians were confused about how to document biosimilar use. That’s not because they’re careless-it’s because the naming system is messy.

That’s where product identification comes in. The FDA started requiring unique four-letter suffixes in 2017-like "-atto" for Amjevita. But many providers still use brand names like "Humira" even when the patient got the biosimilar. Health Canada doesn’t use suffixes. Instead, they require the manufacturer’s name to be clearly documented. In Spain, hospitals started tagging biosimilars in electronic records in 2020. Result? Adverse event reporting accuracy jumped from 58% to 92%.

Active surveillance is the other half. Systems like the FDA’s Sentinel Initiative scan millions of insurance claims and electronic health records. They look for patterns-like a spike in hospital visits for joint pain after a new biosimilar hits the market. These systems don’t wait for someone to report a problem. They find it first.

Regulatory Differences Around the World

Each country handles biosimilar safety differently. The European Union treats all biologics the same, whether they’re original or biosimilar. Their system is built on consistency. The U.S. takes a hybrid approach. Biosimilar makers must submit safety reports every six months for the first two years, then annually. They also have to use those four-letter suffixes. Canada goes further: their guidelines require manufacturers to prove they can distinguish their product’s adverse events from the reference product’s. That means every report must include the manufacturer’s name, batch number, and product code.

Why does this matter? Because if 10 different biosimilars all target the same reference drug-like infliximab-and they all have similar names, it becomes impossible to tell which one caused a reaction. A 2015 study warned this would happen. And it did. In 2022, the U.S. approved 10 new biosimilars. That’s 10 new products with similar names, similar uses, and similar side effect profiles. Without clear labeling, safety systems can’t tell them apart.

Real-World Challenges for Doctors and Patients

Healthcare providers are on the front lines. A rheumatologist in Baltimore told Medscape in 2023: "I’ve had three cases where the pharmacy switched the drug without telling me. I didn’t know if the patient got the biosimilar or the original. When they had a reaction, I couldn’t report it properly." That’s not rare. A 2021 study found only 37.8% of U.S. pharmacists knew what information was required to report a biosimilar adverse event.

Patients are even more confused. The Arthritis Foundation’s 2022 survey showed 41.2% of people on biosimilars didn’t know which product they were taking. They got a prescription, walked into the pharmacy, and were handed a vial with a different name. No explanation. No warning. That’s not just bad communication-it’s a safety gap. If a patient has a reaction and can’t tell their doctor what they took, the entire safety system breaks down.

On the flip side, countries that made tracking mandatory saw big improvements. In Denmark, after analyzing 2015 data, the health authority found no difference in safety between biosimilars and their reference products. That’s because they had clear reporting rules. In Canada, since January 2023, failing to report the manufacturer’s name in an adverse event report can cost a company up to $500,000. That’s a strong incentive to get it right.

The Role of Technology and AI

Manual reporting isn’t enough anymore. The volume of data is too high. That’s why regulators and companies are turning to AI. The EMA launched VigiLyze in 2022-an AI tool that scans 1.2 million new case reports every year. It flags unusual patterns with 92.4% accuracy. It doesn’t replace humans, but it finds needles in haystacks.

Some companies are using natural language processing to read doctor’s notes in electronic records. If a clinician writes, "Patient had infusion reaction after switch to biosimilar," the system picks it up-even if the product name wasn’t coded correctly. These tools are expensive. Mid-sized pharmaceutical companies spend $250,000 to $500,000 to implement them. But the cost of missing a safety signal? That’s far higher.

What’s Next for Biosimilar Safety?

The global biosimilars market is growing fast. It was worth $7.3 billion in 2022. By 2028, it could hit $34.9 billion. More products mean more complexity. Right now, there are 43 approved biosimilars in Europe and 35 in the U.S. That number will keep climbing. By 2030, the WHO predicts over 300 biosimilars will be on the market, targeting just 30 reference drugs.

That’s why a global solution is needed. The International Pharmaceutical Regulators Programme is pushing for a universal tracking system-like a barcode for every vial of biologic, down to the batch number. Pilot studies in Switzerland show this could cut attribution errors by 73.5%. The catch? It would cost $1.8 billion to roll out worldwide. But compared to the cost of a single major safety failure? It’s a bargain.

For now, the best thing patients and providers can do is demand clarity. Ask: "Which product am I getting?" Write it down. Report side effects clearly. And if you’re a provider, don’t assume the pharmacy told the patient the name. Document it yourself. Because in biosimilar safety, the smallest detail-the right suffix, the correct batch number, the clear note in the chart-can make the biggest difference.

How to Stay Safe When Using Biosimilars

• Always ask your pharmacist: "Is this the reference product or a biosimilar? What’s the manufacturer?"
• Keep a written record of every drug you receive, including the name and batch number if available.
• If you experience a new or worsening side effect, report it to your doctor immediately-and specify the exact product name.
• Don’t assume your electronic health record has the right information. Double-check it with your provider.
• Support policies that require clear labeling and mandatory traceability in your country.

What Patients and Providers Should Do Now

The system isn’t perfect. But it’s working. Countries with clear rules and strong documentation have better safety data. The goal isn’t to stop biosimilars-it’s to make them safer. Every patient deserves access to affordable treatment. But they also deserve to know exactly what’s in their IV bag. Providers need better training. Pharmacies need better systems. Regulators need more data. And patients need to speak up. If you’re on a biosimilar, ask questions. Write things down. Report side effects. Because in biosimilar safety, awareness isn’t just helpful-it’s essential.