---
title: "Free Radicals — Glossary | School of Dermatology"
url: https://schoolofdermatology.com/glossary/free-radicals
description: "Learn what free radicals are, how they damage your skin and accelerate aging, and which antioxidants can protect against oxidative stress."
lang: en
---

Glossary

# Free Radicals

free RAD-ih-kulz

## Definition

Free radicals are unstable, reactive molecules with unpaired electrons that damage cells by stealing electrons from other molecules in a chain reaction process called oxidative stress. In the skin, free radicals are generated primarily by UV radiation, air pollution, cigarette smoke, and even normal metabolic processes. They attack cell membranes, DNA, collagen, and elastin fibers, accelerating skin aging, promoting hyperpigmentation, and contributing to skin cancer risk. The damage accumulates over time and is a major driver of what dermatologists call 'extrinsic aging' — aging caused by external factors rather than genetics. Antioxidants are the body's defense against free radicals; they neutralize these reactive molecules by donating an electron without becoming unstable themselves. Topical antioxidants like vitamin C, vitamin E, and ferulic acid provide an important layer of protection.

## Related Terms

Antioxidant: https://schoolofdermatology.com/glossary/antioxidant
Oxidative Stress: https://schoolofdermatology.com/glossary/oxidative-stress
Vitamin C (Ascorbic Acid): https://schoolofdermatology.com/glossary/vitamin-c-ascorbic-acid
Collagen: https://schoolofdermatology.com/glossary/collagen

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