The FDA doesn’t just issue guidelines-it enforces them. When manufacturers cross the line, the agency doesn’t wait. It acts. And those actions start with something simple but powerful: a warning letter.
Think of a warning letter not as a polite reminder, but as the FDA’s first official shot across the bow. It’s not a fine. It’s not a shutdown. But it’s the moment when a company realizes the agency is watching-and that things are about to get serious. Since the 1970s, this tool has been the backbone of FDA enforcement. And in recent years, it’s become more aggressive than ever.
What Exactly Is an FDA Warning Letter?
An FDA Warning Letter is a formal notice sent to a company after an inspection or complaint reveals serious violations of federal law. It doesn’t come out of nowhere. It follows an FDA inspector walking through a factory, reviewing records, or sampling products. If they find problems that put public health at risk, they document them on FDA Form 483 a checklist of observations made during inspections, often used as the basis for a warning letter. Then, if those issues are significant enough, the FDA sends the warning letter.
These letters don’t mince words. They list each violation-exactly where it happened, what regulation was broken, and why it matters. A food plant might be cited for failing to prevent cross-contamination. A drugmaker might be told its quality control records are incomplete. A telehealth company might get flagged for advertising compounded drugs as FDA-approved when they’re not.
Companies get 15 business days to respond. That’s not a suggestion. It’s a deadline. Miss it, and the FDA moves to the next level: civil penalties, import bans, or even product recalls.
How the FDA Escalates Enforcement
The warning letter is just the beginning. The FDA has a full toolbox, and it’s getting used more than ever.
- Untitled Letters less severe notices for minor issues, often used for promotional violations before escalating to formal warning letters: These are for smaller problems-like misleading ads or minor labeling errors. They’re not as serious as warning letters, but they still go on record.
- Import Alerts a formal notice that the FDA will detain products at the border without physical inspection due to prior violations: If a foreign manufacturer has a history of violations, the FDA can put them on an Import Alert. That means every shipment gets automatically stopped at the port. The company has 30 days to prove it’s fixed the problem-or the product gets destroyed.
- Recall Notices official requests for manufacturers to remove unsafe products from the market, either voluntary or mandatory: Sometimes, the FDA doesn’t wait for a response. If a product is dangerous, it’s pulled-fast. In 2024, over 300 recalls were initiated by the FDA across food, drugs, and medical devices.
- Withdrawal of Approval complete removal of a product’s authorization to be sold in the U.S., used for persistent or severe violations: This is the nuclear option. If a company keeps violating rules, the FDA can yank approval for the entire product. Once that happens, the company can’t sell it again unless it reapplies-and that’s a long, expensive process.
And then there’s the threat of criminal charges. Under Section 303(f) of the Federal Food, Drug, and Cosmetic Act, anyone who delays, denies, or limits an FDA inspection can face jail time. That includes redacting documents, refusing access to parts of a facility, or lying to inspectors. In 2025, the FDA expanded its unannounced inspections of foreign facilities-and with them, the number of criminal referrals.
Where the FDA Is Most Active Right Now
The FDA isn’t treating all industries the same. Some are under heavier scrutiny than others.
Tobacco products are getting hit hardest. Since 2021, the FDA has issued over 700 warning letters targeting companies selling unauthorized e-cigarettes and vaping devices. Most of these products appeal to teens and lack the required marketing authorization. The agency has made this a top priority, even as some companies challenge its legal authority in court.
Pharmaceutical compounding is the new frontier. In the first half of 2025 alone, the FDA issued 58 warning letters to telehealth companies and compounding pharmacies selling fake versions of popular weight-loss drugs like semaglutide and tirzepatide. These aren’t FDA-approved drugs. They’re mixed in labs, marketed as "similar," and sold online with no oversight. The FDA says this puts patients at risk-and it’s cracking down hard.
Food manufacturing is also under modernized scrutiny. In 2024, the FDA issued 149 warning letters to human food facilities and 37 to animal food facilities. The violations? Not just outdated sanitation. Now, they’re citing failures under the Food Safety Modernization Act (FSMA)-like not having a proper hazard analysis or failing to implement preventive controls. This shift means companies can’t rely on old practices. They need science-based food safety plans.
What Happens After the Warning Letter?
Receiving a warning letter isn’t the end. It’s the start of a race.
Companies have to act fast. They need to assemble a team: quality control, legal counsel, regulatory affairs, and senior leadership. They have to fix the problem, document every step, and send a detailed response to the FDA within 15 days. That response isn’t just a letter. It’s evidence. Photos. Training logs. Updated procedures. Lab results.
The FDA reviews it. If they’re satisfied, the case closes. If not? The next step is a Civil Monetary Penalty fines ranging from $10,000 to $1 million per violation, imposed for failure to correct FDA-identified violations. These aren’t small. One company in 2025 was fined $750,000 for failing to correct cGMP violations in its sterile injectable drug production.
And if the company still doesn’t comply? The FDA can seize products, shut down operations, or refer the case to the Department of Justice for criminal prosecution.
Why This Matters to Everyone
You might think this only affects big pharma or foreign factories. But it affects you.
When a company cuts corners on drug quality, it’s your medicine that might be ineffective. When a food plant ignores contamination controls, it’s your baby’s formula or your pet’s food that could be contaminated. When a telehealth site sells unapproved weight-loss drugs, it’s your health on the line.
The FDA’s warning system isn’t about punishment. It’s about prevention. It’s a way to catch problems before they hurt people. And right now, the agency is doubling down.
Under Commissioner Robert Califf, the FDA has returned to the enforcement levels of the 1990s-issuing hundreds of warning letters a year. That’s not a coincidence. It’s a strategy. The agency is no longer waiting for disasters to happen. It’s trying to stop them before they start.
What Companies Need to Do
If you’re a manufacturer, here’s the bottom line:
- Don’t ignore inspection notices. Treat them like emergencies.
- Don’t assume your overseas supplier is compliant. Verify everything.
- Don’t use marketing language that implies FDA approval unless you have it.
- Don’t wait until the warning letter arrives to fix problems. Audit yourself regularly.
Regulatory compliance isn’t a box to check. It’s a culture. And the FDA is watching.
What happens if I ignore an FDA warning letter?
Ignoring an FDA warning letter almost always leads to escalation. The agency may issue a Civil Monetary Penalty (up to $1 million per violation), detain your products at the border through an Import Alert, initiate a recall, or even pursue criminal charges. The FDA does not typically wait long before taking stronger action if a company fails to respond adequately.
Can the FDA shut down a manufacturing facility?
Yes. While the FDA doesn’t directly shut down facilities, it can issue a withdrawal of approval for a product, which effectively stops sales. It can also seize products, issue injunctions through federal courts, or refer cases for criminal prosecution-all of which can force a facility to close until compliance is achieved. In extreme cases, the agency has worked with the Department of Justice to obtain court orders that halt operations entirely.
Are warning letters public?
Yes. All FDA warning letters are published on the agency’s website within days of being issued. They’re searchable by company name, product type, and date. This transparency is intentional-investors, customers, and competitors can all see which companies are out of compliance. Many companies lose business or face investor pressure after a warning letter becomes public.
How long does it take to get a warning letter after an inspection?
There’s no fixed timeline, but most warning letters are issued within 30 to 90 days after an inspection. The FDA first issues an FDA Form 483 at the end of the inspection listing observations. If those observations point to serious violations, the agency drafts a warning letter. The delay allows time for legal review and internal approval, especially since warning letters are now signed by senior officials like the CDER or CBER Director.
Do foreign manufacturers get the same treatment as U.S. ones?
Yes. The FDA has equal authority over foreign manufacturers selling products in the U.S. In fact, over 70% of FDA inspections now occur overseas. Foreign facilities face the same warning letters, import alerts, and potential criminal penalties. The agency has increased unannounced inspections of foreign sites by 300% since 2025, making it harder for overseas companies to avoid compliance.
Can a company appeal an FDA warning letter?
There’s no formal appeal process for warning letters themselves-they’re not legally binding orders. But companies can request a meeting with the FDA to discuss the findings, submit additional evidence, or ask for clarification. If the FDA proceeds to more severe actions like a seizure or injunction, the company can challenge those in federal court. However, most companies focus on correcting the violations rather than fighting the letter.
