1-Hydroxyethyl 4,5-Diamino Pyrazole Sulfate

1-Hydroxyethyl 4,5-Diamino Pyrazole Sulfate and pregnancy

Not Recommended

• Absorbed into the body

1-Hydroxyethyl 4,5-Diamino Pyrazole Sulfate is a hair dye intermediate used in permanent and semi-permanent hair coloring products. It penetrates the hair shaft and can be absorbed through the scalp, especially during extended contact times typical of hair coloring. While specific studies on this particular compound during pregnancy are limited, ACOG states that limited data suggests hair dye use during pregnancy is likely safe, though recommends extra caution during the first trimester when fetal development is most critical. Chemical hair dyes involve some systemic absorption, and many obstetricians recommend waiting until after the first trimester or using highlighting techniques that minimize scalp contact. Most dermatologists advise pregnant women to minimize exposure to hair dye chemicals, particularly in the first trimester. Semi-permanent or vegetable-based dyes may be preferred alternatives. If using permanent dyes, ensure good ventilation, minimize scalp contact time, and wear gloves during application.

1-Hydroxyethyl 4,5-Diamino Pyrazole Sulfate and breastfeeding

Safe to Use

As a hair dye ingredient applied to the scalp, 1-Hydroxyethyl 4,5-Diamino Pyrazole Sulfate has limited systemic absorption during typical use. The compound remains primarily localized to the hair and scalp area. While specific breastfeeding studies are not available, the AAD notes that hair dye use during breastfeeding is generally considered acceptable. Any absorbed amount would be minimal and unlikely to transfer to breast milk in significant quantities. Standard precautions include ensuring good ventilation and following manufacturer instructions. Breastfeeding women can use hair dye products containing this ingredient with minimal concern. Avoid prolonged skin contact, ensure proper ventilation, and do not apply near the breast area.

1-Hydroxyethyl 4,5-Diamino Pyrazole Sulfate and postpartum

Safe to Use

• Common allergen

For postpartum women not breastfeeding, this hair dye ingredient presents minimal concerns beyond standard allergic reaction risks. The primary consideration is skin sensitivity, which may be heightened postpartum. Postpartum hormonal changes can affect skin sensitivity, so patch testing before use is advisable. Otherwise, this ingredient can be used according to standard hair dye safety guidelines without additional restrictions.

1-Hydroxyethyl 4,5-Diamino Pyrazole Sulfate and trying to conceive

Safe to Use

For women trying to conceive, hair dye ingredients like 1-Hydroxyethyl 4,5-Diamino Pyrazole Sulfate present minimal concerns. There is no evidence linking hair dye use to reduced fertility or conception difficulties. While some women choose to adopt conservative practices when trying to conceive, occasional hair dye use is not considered a fertility concern. If desired, waiting until pregnancy is confirmed or using highlighting techniques that minimize scalp contact are options for extra caution.

1-Hydroxyethyl 4,5-Diamino Pyrazole Sulfate and PCOS

Safe to Use

1-Hydroxyethyl 4,5-Diamino Pyrazole Sulfate is a hair dye chemical with no known hormonal activity or endocrine-disrupting properties. It does not affect androgen levels, insulin sensitivity, or other metabolic factors relevant to PCOS. The ingredient functions purely as a coloring agent without interacting with hormone pathways. Women with PCOS may use hair dyes containing this ingredient without concern for hormonal effects. Standard precautions for hair dye use apply. The ingredient poses no special concerns for women with PCOS beyond the typical considerations of potential allergic reactions that apply to all users.

1-Hydroxyethyl 4,5-Diamino Pyrazole Sulfate and general use

Safe to Use

• Common allergen
• Irritant

As a hair dye intermediate, this ingredient is used in professional and at-home hair coloring products. It helps achieve stable, long-lasting color results in oxidative dye systems. The main concern with this ingredient is potential allergic contact dermatitis, which can affect sensitive individuals. The SCCS has evaluated pyrazole derivatives for safety in hair dyes, establishing concentration limits. Patch testing before use is strongly recommended, especially for those with a history of dye allergies or sensitive skin. When used according to product instructions, this ingredient is considered acceptably safe for cosmetic use. Always perform patch tests, ensure good ventilation during application, avoid contact with eyes, and follow timing instructions to minimize irritation risk.

Everything else flagged for the same profiles

• Flagged in pregnancy

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Ingredients suggested in place of 1-Hydroxyethyl 4,5-Diamino Pyrazole Sulfate, each one with its own page here.

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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.