Does Dry Shampoo Cause Hair Loss? What Is Documented

Dry shampoo does not cause pattern hair loss, and no regulator has said it does. The question became popular for a specific reason — a wave of recalls in 2022 — and those recalls were about something else entirely. Here is what is on the record.

What the 2022 recalls were actually about

On 18 October 2022 Unilever United States issued a voluntary recall to the consumer level of selected lot codes of aerosol dry shampoo products made before October 2021, across several of its brands, because of potentially elevated levels of benzene. Procter & Gamble had issued its own voluntary recall of aerosol dry shampoo and dry conditioner sprays. In the Unilever recall, an internal investigation identified the propellant as the source.

Benzene is a human carcinogen and has no business in a consumer aerosol, which is why the recalls happened. But a contamination problem in a propellant is a different subject from whether a product makes hair fall out. The recall notices are about cancer risk from a contaminant, not about alopecia, and reading one as evidence of the other is a category error that a lot of coverage made.

What is documented about cleansing products and hair loss

There is a real case on the record, and it is not about dry shampoo. The FDA began receiving voluntary adverse event reports of hair loss associated with cleansing conditioners in 2011 and announced in July 2016 that it was investigating. It commissioned work at Columbia University's dermatology department to look at the mechanisms of hair loss associated with the use of selected cosmetic hair products.

The study looked at two named cleansing products and five shared ingredients. Mice treated with either product over a prolonged period showed abnormal hair growth cycles. The agency's own summary is careful: it was unable to draw a firm connection between the use of certain hair cleansing products and ingredients, and alopecia, and it continues to monitor reports. That is the state of the evidence — a signal worth watching, not a proven cause. The longer version is in shampoos that cause hair loss: the myths and the one real case.

Why dry shampoo gets blamed anyway

Three ordinary things line up to make it look guilty, and none of them is hair loss.

• People reach for dry shampoo when they are already washing less — during illness, stress, a new baby, a demanding job. Those are also the classic triggers for telogen effluvium, a diffuse shed that begins some time after the trigger rather than during it. The dry shampoo arrives at the same time as the shedding, and gets the blame.
• Build-up at the roots can make a scalp itch and flake, and scratching an irritated scalp breaks hairs. Broken hair looks like lost hair in a hairbrush.
• Washing less means each wash releases several days of hairs that had already been shed and were held in place by the rest of your hair. A larger clump in the drain after a gap is arithmetic, not a new problem.

Checking whether something you own was recalled

Recalls are specific, not general. Both 2022 notices name brands and lot codes rather than whole product lines, and the Unilever notice covers aerosol dry shampoos produced before October 2021. The recall notices themselves are published on the FDA's recalls and safety alerts pages, with the affected lot codes listed, which is the only reliable place to check a can you already have.

Two things are worth keeping straight while you look. Unilever's notice states that based on an independent health hazard evaluation, daily exposure to benzene at the levels detected would not be expected to cause adverse health consequences, and that it had received no reports of adverse events relating to the recall. That is the company's own summary of its own assessment, reproduced in the notice. And none of it is a statement about hair.

The other reason people ask: build-up

The second common route to this question is not shedding at all. Dry shampoo works by absorbing oil, which means leaving powder on the scalp, and on some people that accumulates into itching, flaking and a scalp that feels tight or sore. An uncomfortable scalp is a real problem in its own right and it is treatable — and it is also a scalp condition rather than a hair-loss one, which means the answer sits on a different shelf.

The two best-graded actives in the hair-loss aisle happen to be the actives in ordinary medicated anti-dandruff shampoos, which is a coincidence worth knowing if your scalp is flaking as well as your hair thinning. What each one has actually been shown to do is set out in what the ketoconazole shampoo evidence actually shows.

What would actually be worth investigating

If your hair is shedding and you want to know whether a product is involved, the useful questions are medical rather than cosmetic. Is the scalp itself inflamed, flaking or sore? Did it begin in the months after an illness, an operation, a birth, a crash diet or a new medicine? Is the hairline receding in a pattern, or is the whole head thinner? Those distinctions are what a GP or a dermatologist is for, and they point at completely different answers.

Stopping a product for a few weeks to see what happens is harmless and occasionally informative. Replacing it with an expensive product marketed at hair loss, before anyone has established what is causing the loss, is how people spend a year on the wrong shelf. Everything in that aisle, graded, is in the best shampoo for hair loss, graded on published evidence.