Arnica (Arnica montana) is a plant-derived extract used in topical formulations for its purported anti-inflammatory and soothing effects, often marketed for bruising and skin irritation. Its key constituents include sesquiterpene lactones such as helenalin.
| Reported effect | How often | Notes |
|---|---|---|
Allergic contact dermatitis | Common | Sesquiterpene lactones are well-documented sensitizers, particularly in those allergic to Asteraceae/Compositae plants. |
Skin irritation, redness, or itching | Uncommon | May occur with topical application, especially on broken or sensitive skin. |
Eczematous flare or worsening dermatitis | Rare | Reported with prolonged or repeated use in sensitized individuals. |
Systemic toxicity | Very rare | Associated with ingestion or use on large broken-skin areas; topical cosmetic use rarely causes systemic effects. |
Frequencies reflect typical cosmetic use reported in the literature, not a guarantee for your skin.