Class I · II · III — Overview
Class I — General Controls
Risk level: Lowest
Controls: General controls only
Market pathway: Most are 510(k)-exempt; a small number require 510(k)
Class I devices are those for which general controls alone are sufficient to provide reasonable assurance of safety and effectiveness. They present minimal potential for harm and are typically simple in design.
Examples: Bandages, tongue depressors, elastic bandages, non-powered wheelchairs, examination gloves
Key facts:
- Approximately 47% of all device types are Class I
- The vast majority (~95%) of Class I devices are exempt from 510(k)
- General controls still apply — registration, listing, QMS, MDR, labelling
Class II — Special Controls
Risk level: Moderate
Controls: General controls + special controls
Market pathway: 510(k) clearance (most); some are exempt
Class II devices require more than general controls to provide assurance of safety and effectiveness. Special controls — device-specific performance standards, post-market surveillance requirements, or FDA guidance — supplement the general controls baseline.
Special controls are established:
- By FDA in a classification regulation (21 CFR Parts 862–892)
- Through a De Novo order (which creates new special controls)
Examples: Powered wheelchairs, infusion pumps, surgical drapes, X-ray film, blood pressure monitors, most IVD diagnostics
Key facts:
- Approximately 43% of all device types are Class II
- 510(k) clearance is the standard pathway — demonstrates substantial equivalence to a predicate
- De Novo results in a new Class II device type with special controls
Class III — Premarket Approval
Risk level: Highest
Controls: General controls + PMA
Market pathway: Premarket Approval (PMA)
Class III devices support or sustain human life, are of substantial importance in preventing impairment of human health, or present a potential, unreasonable risk of illness or injury. The safety and effectiveness of these devices cannot be assured by general or special controls alone.
Examples: Implantable pacemakers, implantable defibrillators, deep brain stimulators, breast implants, total artificial hearts, certain neurovascular stents
Key facts:
- Approximately 10% of device types are Class III
- PMA requires valid scientific evidence — typically including clinical data from IDE-approved trials
- PMA is "approved," not "cleared" — a meaningful regulatory distinction
- Changes to approved PMAs require supplements
The 510(k) exemption concept
Being Class I or II does not automatically mean 510(k) is required. Exemptions exist when FDA has determined that 510(k) is not needed for general controls to be sufficient. Exemptions may be limited — e.g., capped at a certain complexity level. Check the specific 21 CFR classification regulation for exemption status and any limitations.
Comparison table
| Feature | Class I | Class II | Class III |
|---|---|---|---|
| Risk | Low | Moderate | High |
| Controls | General | General + Special | General + PMA |
| Typical pathway | Exempt | 510(k) | PMA |
| % of device types | ~47% | ~43% | ~10% |
| Examples | Bandages, tongue depressors | Infusion pumps, X-ray | Pacemakers, defibrillators |
| FDA decision term | N/A | Clearance | Approval |