Kathon CG

Kathon CG and pregnancy

Safe to Use

• Irritant
• Common allergen

Kathon CG is a preservative blend used to prevent microbial contamination in cosmetic products. While effective at preserving products, it's known for causing contact dermatitis and skin sensitization in many individuals. The primary concern during pregnancy is not fetal toxicity but rather increased skin sensitivity. Pregnancy hormones can make skin more reactive, potentially increasing the risk of allergic reactions or irritation from this already problematic preservative. According to the European Contact Dermatitis Society, pregnant women with a history of skin sensitivities should be particularly cautious with known allergens. However, there is no evidence that topical use of Kathon CG at permitted concentrations poses risks to fetal development. ACOG does not specifically address cosmetic preservatives in pregnancy guidelines, and the FDA has not issued pregnancy-specific warnings about Kathon CG. The concern is primarily dermatological rather than obstetric. Pregnant women may choose to avoid this ingredient due to irritation potential, especially since pregnancy already increases skin sensitivity. Consider products with gentler preservatives if you have sensitive skin or a history of contact dermatitis. If you prefer to avoid Kathon CG during pregnancy due to irritation concerns, look for products preserved with gentler alternatives like phenoxyethanol, sodium benzoate, or potassium sorbate.

Kathon CG and breastfeeding

Safe to Use

• Irritant
• Common allergen

Kathon CG is a preservative known for its allergenic and irritating properties. While it effectively prevents product contamination, it has a high rate of causing contact dermatitis. For breastfeeding mothers, the main concern is skin irritation rather than transfer to breast milk. Topical preservatives have minimal systemic absorption and are unlikely to affect breastfed infants. However, if products containing Kathon CG are used on or near the chest area, there is a theoretical risk of the infant coming into direct contact with the product, which could cause skin irritation on the baby's sensitive skin. The American Academy of Dermatology recommends that breastfeeding mothers avoid applying potentially irritating ingredients to areas that will contact the infant's skin. If using products with Kathon CG, apply them to areas away from the chest or ensure products are fully absorbed and dried before breastfeeding. Many dermatologists recommend choosing products with gentler preservatives during the breastfeeding period. Consider alternatives like phenoxyethanol, sodium benzoate, or naturally-derived preservatives if you're concerned about potential infant exposure or have sensitive skin.

Kathon CG and postpartum

Safe to Use

• Irritant
• Common allergen

Kathon CG remains a preservative of concern postpartum due to its high allergenicity and irritation potential. Postpartum hormonal changes can continue to affect skin sensitivity, making reactions more likely. For postpartum women not breastfeeding, the primary concern is the same as for the general population: a high risk of developing allergic contact dermatitis with repeated exposure. If you have sensitive skin or a history of allergies, choosing products with gentler preservatives may be preferable during the postpartum period when your skin may still be adjusting hormonally.

Kathon CG and trying to conceive

Safe to Use

• Irritant
• Common allergen

Kathon CG is a topical preservative with minimal systemic absorption. There is no evidence that it affects fertility, hormone levels, or reproductive function. Women trying to conceive can use products containing Kathon CG without concerns about fertility impact. The primary consideration is skin sensitivity and potential for allergic reactions, not reproductive effects. If you're planning pregnancy, you may wish to transition to products with gentler preservatives to avoid developing new sensitivities, but this is a comfort consideration rather than a fertility concern.

Kathon CG and PCOS

Safe to Use

• Irritant
• Common allergen

Kathon CG is a cosmetic preservative with no hormonal activity or impact on androgen levels. It does not affect PCOS symptoms or hormone balance. For women with PCOS, the concern with Kathon CG is purely dermatological. While it doesn't affect hormones, the irritation and sensitization it can cause may exacerbate existing skin issues common with PCOS, such as acne or inflammation. According to the American Contact Dermatitis Society, individuals with compromised skin barriers or inflammatory skin conditions may be more susceptible to sensitization. Women with PCOS who already deal with acne-prone or sensitive skin may benefit from choosing products with gentler preservative systems to avoid additional irritation that could complicate their skin care routine. Consider products preserved with phenoxyethanol, sodium benzoate, or other less sensitizing alternatives.

Kathon CG and general use

Caution Advised

• Common allergen
• Irritant

Kathon CG is a preservative blend of methylchloroisothiazolinone (MCI) and methylisothiazolinone (MI) used to prevent microbial contamination in cosmetic products. While highly effective, it has gained notoriety as one of the most common causes of cosmetic-related allergic contact dermatitis. According to the American Contact Dermatitis Society, which named methylisothiazolinone Allergen of the Year in 2013, this preservative can cause significant skin reactions including redness, itching, burning, and rash. The European Scientific Committee on Consumer Safety (SCCS) has expressed serious concerns, leading to regulatory restrictions. Studies show that repeated exposure increases sensitization risk, meaning even people without initial reactions can develop allergies over time. Reactions can range from mild irritation to severe contact dermatitis requiring medical treatment. The EU has banned MI in leave-on products entirely and severely restricted it in rinse-off products to 0.0015%. The MCI/MI mixture is limited to 0.0015% in all cosmetic products in the EU. While the FDA has not implemented similar bans in the US, the dermatology community increasingly recommends avoiding these preservatives, especially for individuals with sensitive skin, eczema, or a history of allergies. Many major cosmetic brands are reformulating to remove these ingredients due to consumer concerns and regulatory pressure. If you have sensitive skin, a history of contact dermatitis, or want to minimize allergen exposure, look for products preserved with alternatives like phenoxyethanol, sodium benzoate, potassium sorbate, or naturally-derived preservative systems.

Everything else flagged for the same profiles

Related ingredients

Ingredients suggested in place of Kathon CG, each one with its own page here.

• Phenoxyethanol
• Sodium Benzoate
• Potassium Sorbate

Ingredients that raise the same concerns.

• Parfum/FragranceIrritant, Common allergen
• Lavandula Angustifolia OilIrritant, Common allergen
• Melaleuca Alternifolia Leaf OilIrritant, Common allergen
• MethylisothiazolinoneIrritant, Common allergen
• EugenolIrritant, Common allergen

Where this came from

Truva summarises published guidance from bodies including ACOG, the FDA, the EU SCCS and the Cosmetic Ingredient Review. It has no access to your medical history and it is not a substitute for your doctor, dermatologist or midwife. These assessments have not been reviewed by a clinician, and nothing here is a diagnosis or a prescription. If you are pregnant, breastfeeding or being treated for PCOS, take the ingredient list to the person looking after you.

Assessment last pulled from the ingredient database on 15 September 2026.