Sulfur — Allergy Risk & Safety Profile
INCI: SULFUR
Key Facts
- CAS Number
- 7704-34-9
- Category
- active
- Risk Level
- low
- Common Allergen
- No
- Found In
- acne treatment, mask
Is Sulfur safe in cosmetics?
Sulfur is rated low risk in cosmetic products. It is not classified as a common allergen and is generally well-tolerated by most skin types. Commonly found in acne treatment, mask.
What is Sulfur?
Antibacterial and keratolytic. Used for acne and seborrheic dermatitis.
Allergy & Safety Information
Sulfur is considered safe for cosmetic use. No significant safety concerns have been identified at typical use concentrations. As with any cosmetic ingredient, discontinue use if irritation occurs.
This ingredient is considered low risk from an allergenicity perspective. Reactions are uncommon at typical cosmetic use concentrations. However, no ingredient is universally safe — if you notice redness, itching, or irritation after using a product containing this ingredient, discontinue use and monitor whether symptoms resolve.
About Active Ingredient Ingredients
Active ingredients are formulated to produce a specific skin benefit — exfoliation, brightening, anti-ageing, or acne treatment. They work by interacting directly with skin biology, which also means they carry higher irritation potential than passive ingredients like emollients or thickeners.
Relevance for Sulfur: Actives often require an adjustment period during which temporary redness, dryness, or sensitivity is normal. However, persistent reactions after 4–6 weeks of use, or reactions that worsen rather than improve, suggest true intolerance. Introduce only one active at a time to identify the cause of any reaction.
How to Identify Sulfur in Products
Cosmetic ingredients are listed by their INCI (International Nomenclature of Cosmetic Ingredients) name in descending order of concentration. To check whether a product contains Sulfur, scan the ingredient list for its INCI name exactly as it appears above. Ingredients present at 1% or less may appear in any order after the 1% threshold.
Product types to prioritise checking: Acne treatment, Mask. These product categories are the most common sources of Sulfur exposure based on formulation data.
Not sure if your products contain Sulfur? Paste the ingredient list into the free ingredient checker to scan for Sulfur and other allergens automatically.
Frequently Asked Questions
Is Sulfur safe for sensitive skin?
Sulfur is generally well-tolerated, even by sensitive skin types.
What products contain Sulfur?
Sulfur is commonly found in acne treatment, mask.
What does Sulfur do in cosmetics?
Sulfur functions as a active in formulations.
Related Guides
Anti-Aging for Sensitive Skin
The safest actives for sensitive skin and how to use them.
How to Read Ingredient Labels
Decode INCI names and find hidden allergens in your products.
Find Your Skin Allergy Trigger
Step-by-step elimination method to identify your trigger.
Contact Dermatitis Guide
Symptoms, causes, patch testing, and treatment options.
Is Sulfur causing YOUR skin reactions?
SkinDetekt tracks your products and reactions to find your personal triggers. Download the app to find out.
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