Medicated with Menthol Dandruff Shampoo

The base most products are built on. It carries the other ingredients and has no safety concern.

A foaming cleansing agent from the same sulfate family as sodium lauryl and laureth sulfate. Like its relatives it can be drying or irritating at high concentration or with prolonged contact, especially on already-compromised skin, but at the levels and rinse-off use typical of shampoos and body washes it is considered safe.

A coconut-derived amphoteric surfactant used to boost foam and mildness in cleansers and shampoos. CIR has reviewed it as safe as used, but it is one of the more established contact-allergy triggers in personal care, usually traced to manufacturing impurities such as amidoamine and dimethylaminopropylamine (DMAPA) rather than the betaine itself. People with a history of eyelid or scalp dermatitis are more likely to react.

An undisclosed scent blend that can contain dozens of components. The single most common cause of cosmetic contact allergy, and the blend is not itemized, so you cannot see what is in it.

A coconut-derived fatty acid amide used as a foam booster and thickener in shampoos and washes. It is a recognized, if uncommon, contact sensitizer, and because it belongs to the same ethanolamine family reviewed alongside cocamide DEA, formulators are advised to keep it free of nitrosamine-forming contaminants; well-made products with controlled impurity levels are considered acceptable for rinse-off use.

A preservative that works by slowly releasing small amounts of formaldehyde to control microbial growth. This makes it an effective preservative, but people with a known formaldehyde or fragrance-type sensitivity may develop irritation or an allergic reaction, especially with prolonged use of leave-on products.

Used in tiny amounts to set a product to skin-friendly pH. No concern at those levels.

Ordinary salt, used in surfactant-based products like shampoos and body washes to adjust viscosity by interacting with the surfactant micelles. It has no meaningful toxicity concern at cosmetic use levels; the main practical downside is that too much can make a formula feel less mild.