Shampoo and Hair Color: When a Hair Product Has a Drug Label or a Warning

Anti-dandruff shampoo is a drug

Zinc pyrithione is regulated under 21 CFR Part 358 Subpart H, at 0.3% to 2% in shampoo. It is its antifungal action, not any cleansing or conditioning function, that puts it on the drug side of the line. The sign is a Drug Facts panel with the active ingredient and its percentage. An ordinary shampoo has one plain ingredient list and no panel.

Permanent hair color follows a different rule

p-Phenylenediamine (PPD) is classified in the US as a “coal tar hair dye”. Such dyes are exempt from the FDA’s usual premarket color-additive approval, but only on the condition that the product carries a specific caution statement recommending a preliminary patch test before each use. It is an exemption granted in exchange for a warning at the point of use.

The same regulation says the product must not be used for dyeing eyelashes or eyebrows. In the EU, PPD in hair dye is restricted to a maximum of 2% on the head.

How to read a hair product label

1. Look for a Drug Facts panel. If it is there, the product is a drug, and the label shows the active and its percentage.
2. On a hair color, look for the patch-test caution statement. Its presence is part of what the rule requires.
3. Read front-of-pack words knowing that some have no legal definition at all.

“Salon quality” and “professional strength”

Nothing. No FDA definition governs either phrase, and a product can carry either claim regardless of where it is sold or how it is formulated.

When two products have the same active

If two products state the same active ingredient at the same percentage, a price gap does not come from the chemistry. In the volume’s example, a brand-name 5% minoxidil foam and a generic 5% minoxidil solution differ in price because the foam format carried patent protection until 2015, while the solution patent expired in 1996. The Drug Facts panel cannot show you a patent history.

Materials behind these labels

• Zinc Pyrithione — The OTC active in anti-dandruff shampoo, which puts the product on the drug side.
• p-Phenylenediamine (PPD) — The oxidative dye precursor in permanent hair color, sold with a mandated patch-test caution.
• Minoxidil — A hair-regrowth active, sold as an OTC drug with the same kind of Drug Facts panel.

What the full volume adds

This page answers one question from Volume Four — Hair Care. The volume goes further:

• Seven material profiles, with the history and the other uses of each
• What price actually buys here, including the two ways a hair product reaches the shelf as a drug
• Worked examples, including two “keratin treatment” hair masks
• The one-page checklist to print and take shopping

See Volume Four — Hair Care →