The U.S. Food and Drug Administration (FDA) classifies medical devices into three regulatory classes — Class I, II, and III — based on the level of control necessary to provide reasonable assurance of safety and effectiveness. This classification system is codified in 21 USC §360c of the Federal Food, Drug, and Cosmetic Act.
The FDA maintains a database of over 1,700 generic device types across 16 medical specialty panels, each assigned to a regulatory class. New devices are classified by comparison to existing device types or through the De Novo pathway if no predicate exists.
The pathway to market depends on classification: most Class I devices are exempt from premarket review, Class II devices typically require 510(k) clearance (demonstrating substantial equivalence to a predicate), and Class III devices require Premarket Approval (PMA) with clinical trial data.
Scope & Applicability
→Applies to all medical devices marketed in the United States
→Covers instruments, apparatus, implements, machines, implants, in vitro reagents, and similar articles intended for medical use
→Includes Software as a Medical Device (SaMD) and AI/ML-based devices
→Applies to combination products (device + drug/biologic) — classified by primary mode of action
→Does not cover devices intended solely for veterinary use (regulated by USDA)
→Does not cover general wellness products that make only general wellness claims
Classification Classes
I
I
Lowest risk. Subject to General Controls only — establishment registration, device listing, proper labeling, GMP compliance. About 47% of device types are Class I, and most are 510(k)-exempt.
Examples
• Elastic bandages
• Tongue depressors
• Examination gloves
• Hand-held surgical instruments
• Manual stethoscopes
Requirements
✓Establishment registration with FDA
✓Device listing in FDA database
✓Good Manufacturing Practices (21 CFR Part 820)
✓Proper labeling per 21 CFR Part 801
✓MDR (Medical Device Reporting) for adverse events
✓Most are 510(k)-exempt
510k
510k
Moderate risk. Requires premarket notification — a 510(k) submission demonstrating substantial equivalence to a legally marketed predicate device. Special Controls (performance standards, postmarket surveillance, patient registries) may apply in addition to General Controls.
Examples
• Powered wheelchairs
• Infusion pumps
• Pregnancy test kits
• Surgical drapes
• Non-invasive blood pressure monitors
• CT scanners
Requirements
✓510(k) premarket notification
✓Demonstrate substantial equivalence to predicate
✓General Controls + Special Controls
✓QSR / 21 CFR Part 820 compliance
✓MDR reporting obligations
✓Average FDA review: 3–6 months
De Novo
De Novo
For novel low-to-moderate risk devices with no predicate. De Novo creates a new Class II classification with tailored Special Controls, and the device becomes a predicate for future 510(k) submissions.
Examples
• First-of-kind digital health devices
• Novel AI/ML diagnostic tools
• New glucose monitoring technologies
• Innovative wound care devices
Requirements
✓De Novo Request submission to FDA
✓FDA creates new classification regulation
✓Device-specific Special Controls established
✓Device becomes predicate for future 510(k)s
✓Average FDA review: 12–15 months
PMA
PMA
Highest risk — life-sustaining or life-supporting devices, or those presenting unreasonable risk. Requires Premarket Approval (PMA) with valid scientific evidence, typically from clinical trials under an Investigational Device Exemption (IDE).
Examples
• Heart valves
• Coronary stents
• Implantable defibrillators
• Breast implants
• Total hip replacement systems
Requirements
✓Premarket Approval Application (PMA)
✓Clinical trial data (usually under IDE)
✓FDA advisory panel review may be required
✓Annual reports post-approval
✓Post-Approval Studies (PAS) often required
✓Average FDA review: ~180 days (MDUFA clock)
Key Rules & Concepts
Substantial Equivalence (510(k))
→The predicate must be a legally marketed device — cleared via 510(k), De Novo, or classified pre-1976
→Same intended use as the predicate device
→Same technological characteristics — OR different characteristics that do not raise new safety/effectiveness questions
→Performance data may be required to demonstrate equivalence
→FDA issues a "substantially equivalent" (SE) or "not substantially equivalent" (NSE) decision
Software as a Medical Device (SaMD)
→FDA follows the IMDRF framework for SaMD classification
→Classification based on: (1) significance of information provided, and (2) state of healthcare situation
→Clinical Decision Support (CDS) software may be exempt under the 21st Century Cures Act if the clinician can independently review the basis of the recommendation
→AI/ML-based SaMD may follow the Predetermined Change Control Plan (PCCP) pathway
→Digital Health Center of Excellence provides guidance on software regulation
Product Codes & Classification Panels
→Each device type has a 3-letter product code (e.g., QAS for pulse oximeters)
→16 medical specialty panels (Anesthesiology, Cardiovascular, Dental, etc.)
→Classification regulations found in 21 CFR Parts 862–892
→FDA Product Classification Database searchable at accessdata.fda.gov
→Devices can be reclassified by FDA based on new evidence
Exemptions & Special Pathways
→Most Class I and some Class II devices are 510(k)-exempt
→Emergency Use Authorization (EUA) for public health emergencies
→Humanitarian Device Exemption (HDE) for devices treating < 8,000 patients/year
→Breakthrough Device Designation for faster review of innovative devices
→Custom Device Exemption for devices made for individual patients (limited to 5 units/year)
Key Dates
1976
Medical Device Amendments to the FD&C Act — established the three-class system
1997
FDA Modernization Act (FDAMA) — created the De Novo classification pathway