Reporting a side effect to the FDA (MedWatch)

What MedWatch covers

MedWatch is the FDA’s safety reporting program for health professionals, patients and consumers. It takes reports of serious reactions, product quality problems, products that did not work as expected or behaved differently after a switch, and mistakes in how a product was used ^[2].

The current MedWatch page lists prescription and over-the-counter medicines, biologics, medical devices, combination products such as prefilled syringes and auto-injectors, cannabinoid hemp products and cosmetics ^[1]. A faulty pen is therefore reportable in its own right. Some products have their own portals, and the table shows where the FDA sends them; its online page adds that reports sent through MedWatch by mistake are accepted and passed to the right office ^[7].

The reporting line in each label

The FDA’s labeling guidance explains that the Highlights page of a prescribing information carries an adverse reactions reporting statement, with the company’s phone number and the FDA’s phone number and web address, to encourage reports ^[6].

On the Ozempic® label that line gives Novo Nordisk at 1-888-693-6742; Wegovy® gives Novo Nordisk at 1-833-934-6891; Mounjaro® and Zepbound® give Eli Lilly and Company at 1-800-LillyRx (1-800-545-5979). All four add the FDA at 1-800-FDA-1088 and www.fda.gov/medwatch ^{[8][9][10][11]}. The Medication Guides repeat the FDA number for patients and remind you to call your doctor for medical advice about side effects ^[8][9].

What the FDA calls serious

The FDA asks for a report when the outcome of an adverse event is serious. Its definition covers these outcomes ^[3]:

• Death, if you suspect it resulted from the event.
• A life-threatening situation, meaning a real risk of dying at the time.
• Admission to hospital, or a longer stay than planned. An emergency room visit without admission is judged against the other outcomes.
• Disability or lasting damage that substantially disrupts normal life.
• A birth defect possibly linked to exposure before conception or during pregnancy.
• For devices, treatment that was needed to prevent permanent harm.
• Another important medical event that may need treatment to prevent one of the outcomes above, such as an allergic breathing problem treated in an emergency room.

Problems that are not emergencies

The consumer form is not limited to serious events. It is meant for anyone who was hurt or had a bad side effect, including new or worsening symptoms; who used a product incorrectly in a way that could have caused harm; who noticed a quality problem; or who had trouble after switching from one maker to another ^[5]. The online page adds errors caused by look-alike packaging or similar names ^[7].

The FDA explains why such reports matter. Some risks appear only after a product reaches many more patients, for longer, and patients who differ from those studied before approval. Every report is stored and compared with earlier ones, and together they can signal a safety problem ^[4].

Your clinician first, then the report

The FDA’s consumer guidance sets the order: if you have an adverse event, contact your health care professional first, then report it. MedWatch records problems; it does not give medical advice ^[4]. Its online page also reminds you to call 911 in a medical emergency, or 988 in a mental health crisis ^[7].

The FDA encourages you to take the form to your doctor, who can add clinical information such as test results. Your provider is not required to report, though. If they prefer not to, or you would rather do it yourself, you can file the report on your own ^[2].

Three ways to report

• Online: the MedWatch online form, which the FDA calls the quickest and most direct route ^[4]. You can save an unfinished report and complete it within 3 days; once sent it cannot be edited, but you can send a new report that repeats the product and adds what you learned ^[7].
• Paper: Form FDA 3500B, the consumer version, sent by mail or by fax to 1-800-FDA-0178 ^[4][5].
• Phone: 1-800-FDA-1088 on weekdays during working hours (Eastern time); the form prints the same number as 1-800-332-1088 ^[4][5]. The FDA information line, 1-888-INFO-FDA, also connects you to MedWatch ^[2].

What the consumer form asks, section by section

Form FDA 3500B (09/2025 edition) asks you to fill in as much as you can and to send the report even without every answer ^[5]. Its sections cover:

• A, the problem: what kind it was, whether a serious outcome followed, the date, a free description, and any relevant test results.
• B, the product itself: whether you still have it, and photos of all its sides if you can add them. The FDA asks you not to send the product.
• C, the medicine: its name as printed on the package, where and when you bought it (with the website if online), the maker or compounder, whether it is brand, generic or compounded, the expiration date, lot and NDC numbers, strength, amount, how often and how it was used, why you used it, and the dates you started, reduced and stopped it.
• C, continued: whether the problem eased after a dose was reduced or stopped, and whether it came back on restarting.
• D, a device, such as a pen: its name, maker, model, lot, serial and UDI numbers, and who was using it.
• E, the person affected: initials, sex, age, weight, known conditions, allergies, other relevant facts such as pregnancy or alcohol use, and every other medicine, supplement and device in use.
• F, the person filling it in: contact details, whether the maker was told, and a box to keep your identity from the manufacturer.

After you send it

FDA staff enter each report into a database. A safety evaluator, often a pharmacist, doctor or nurse, looks for similar reports, and the agency watches for trends. Possible actions range from safety alerts and label changes to inspections, design or manufacturing changes, a Medication Guide requirement or a recall ^[4].

The form says you will get a reply once it is received, and that the FDA will contact you only if it needs more information. Your name and contact details may be shared with the maker to help it understand the problem unless you tick the box asking otherwise ^[5][7].

Reading the public data

The FDA now describes an Adverse Event Monitoring System (AEMS) that brings its separate reporting systems together, with a public dashboard for searching reports ^[12]. The FDA attaches clear limits to that data: duplicates and incomplete reports exist; a report does not establish that a drug caused the event; the information is not medically verified; and reports cannot give rates of occurrence. It also says patients should talk to their doctor before stopping or changing a medicine ^[12].

So a count of reports for a GLP-1 medicine on the dashboard is not a measure of how often that side effect happens. Rates come from the controlled trials summarised in each label.

Outside the United States

MedWatch is a US system. In the European Union the package leaflet says you can report side effects directly through your national reporting system, and the EU Wegovy® document carries the additional-monitoring statement, which asks for reports so that new safety information is identified quickly ^[13]. If your medicine was dispensed outside the US, the leaflet in your pack names the system to use.

Where your log helps

Most of the form asks for dates and details that are hard to recall weeks later: when a dose was taken, which strength, when it changed, when a symptom began and ended, and the lot and expiry printed on the pen or vial. A dated log turns those questions into copying rather than guessing.

Ozempic® and Wegovy® are registered trademarks of Novo Nordisk A/S. Mounjaro® and Zepbound® are registered trademarks of Eli Lilly and Company. PepLabo is not affiliated with or endorsed by Novo Nordisk or Eli Lilly and Company.

When to get help