Understanding Class I, II, III and Beyond
Before new medical devices can be brought to market, the Food and Drug Administration must decide how the device is to be regulated. This decision is made by evaluating the risk the device poses for future users. Medical devices range from everyday items such as bandages to much more complex technologies, each with its own set of potential risks, so it is important for the FDA to properly assess these risk levels, ensuring patient protection while also encouraging innovation.
The three main categories are Class I, II, and III. These categories provide the framework for device classification; however, there are some exceptions, such as unclassified and enforcement discretion devices. Nonetheless, the majority of products fall under Class I, II, or III.
Class I: Low Risk
Class I devices are the lowest risk and are regulated with general controls, which include proper labeling, good manufacturing practices, and registration with the FDA. Many class I devices are also exempted from pathways, such as a 510(k) Premarket Notification, due to their low risk.
Class II: Moderate Risk
Class II devices pose a larger risk than those of Class I. Because of this, in addition to general controls, they require special controls. These may include post market studies, performance standards, or FDA guidance documents. Most Class II devices will go through the 510(k) process for approval, in which the manufacturer is required to demonstrate how the device is comparable to a device already on the market
Class III: High Risk
Class III devices, usually life-sustaining or implantable devices, pose the greatest risk to future users as they can cause serious potential harm upon failure. Almost all Class III Devices require Premarket Approval (PMA) to provide extensive evidence of the safety and effectiveness of the device, often including clinical trials.
Unclassified and Enforcement Discretion Devices
Although most devices fall into Class I, II, or III, there are a few exceptions. In 1976, the Medical Device Amendments to the FD&C Act were passed, creating a new 3-tier classification system. Devices that were not classified by the original FDA classification panels remain unclassified even after 1976. In other cases, certain very low-risk products fall under enforcement discretion, meaning FDA chooses not to actively enforce all regulatory requirements. While rare, both situations still allow devices to be legally marketed under FDA oversight.
Why Classification Matters
A device’s classification determines the type of review it must undergo, the evidence required, and the level of controls it is subject to. Low-risk products can often reach the market quickly, while higher-risk technologies face stricter requirements to protect patient safety. By tailoring oversight to risk, the FDA balances safety with access to innovative medical technology.
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