Does Onion Shampoo Actually Work? Here Is What the Science Says (and What It Does Not)

Something interesting has happened with the onion shampoo trend. It did not start with a brand campaign. It started with people on TikTok sharing real results, and other people trying it, and more people sharing results. Interest in onion shampoo has grown over 106 percent on Google search, with an average of 3.1 million weekly TikTok views on the topic. That is not a marketing push. That is word of mouth.

So is there something to it? Yes. The science behind onion extract and scalp health is real. But it is also worth understanding what the research actually shows, and what it does not, so your expectations are grounded in something true.

The Science Behind Onion and Hair Health

Onion (Allium cepa) has a high natural sulfur content. Sulfur is one of the most essential nutrients for hair structure. It is a building block of keratin, the fibrous protein that forms the structure of each hair strand. Without adequate sulfur, keratin production slows and hair becomes weaker, thinner, and more prone to breakage.

Beyond keratin support, onion compounds have demonstrated antimicrobial properties that support a healthier scalp environment, and anti-inflammatory activity that may reduce the scalp irritation that can interfere with follicle function. The quercetin content of onion extract also provides antioxidant protection at the scalp surface, where free radical damage is a known contributor to follicle stress.

SCIENCE SPOTLIGHT: Onion Extract and Hair Regrowth: The 2002 Clinical Study

A 2002 peer-reviewed clinical study published in the Journal of Dermatology (Sharquie & Al-Obaidi) tested topical onion juice on 38 patients with patchy alopecia areata. After six weeks of twice-daily application, hair regrowth was observed in 86.9% of the onion-treated group, compared to 13% in the control group. Regrowth of terminal hairs began as early as two weeks into treatment. A 2025 phytotherapy review (WJARR) confirmed that onion oil and extract have been shown to improve hair shaft strength and elasticity, reduce hair breakage, and enhance shine and texture when used as topical treatments, through their sulfur compounds, flavonoids, and antioxidant activity.

Note: The 2002 study involved patients with alopecia areata specifically and is not a claim about any other type of hair loss. Research into onion for androgenetic alopecia is ongoing.

Sources: PubMed 12126069 | WJARR 2025 phytotherapy review

The Science Behind Rosemary for Hair

Rosemary Oil is where the formulated research is strongest. The compound 12-methoxycarnosic acid, present in rosemary extract, has been identified in laboratory studies as an inhibitor of 5-alpha reductase, the enzyme that converts testosterone into DHT. DHT is the primary hormonal driver of progressive hair thinning in both men and women.

In 2015, a landmark randomized comparative trial published in SKINmed compared rosemary oil directly to minoxidil 2% in 100 patients with androgenetic alopecia over six months. Both groups applied their treatment twice daily. At six months, both groups showed significant increases in hair count, and there was no statistically significant difference between the two groups. The rosemary group also reported lower rates of scalp itching than the minoxidil group.

SCIENCE SPOTLIGHT: Rosemary Oil vs. Minoxidil: The 2015 Randomized Trial

A 2015 randomized comparative trial (Panahi et al., SKINmed) compared rosemary oil (3.7 mg/mL, applied twice daily) to minoxidil 2% in 100 patients with androgenetic alopecia over 6 months. Both groups showed significant hair count increases at the 6-month endpoint. No statistically significant difference in hair count was found between the two groups (P > .05). Scalp itching was significantly more frequent in the minoxidil group at both the 3- and 6-month assessments compared to the rosemary group. A 2012 in vivo study (Murata et al.) found that rosemary extract inhibits 5-alpha reductase in a dose-dependent manner, identifying 12-methoxycarnosic acid as the active compound.

Note: This comparison was against minoxidil 2%, which is a lower concentration than the 5% commonly used today. Rosemary is a promising complementary approach, not a pharmaceutical replacement.

Sources: PubMed 25842469 | SKINmed 2015 | ResearchGate rosemary/5AR study

How the Just Nutritive Formula Compares to What Went Viral

The Natural Sant Onion, Biotin and Rosemary Shampoo is the product that drove much of the TikTok conversation. It popularized the onion and rosemary combination and introduced millions of people to the concept. The Just Nutritive formula goes significantly further.

Where Natural Sant focuses on the core onion and rosemary pairing, Just Nutritive builds a 20-plus ingredient formula that adds three natural DHT blockers (Tea Tree Oil, Nettle Extract, Cedarwood Oil), a strengthening protein complex (Hydrolyzed Soy Protein, Hydrolyzed Rice Protein, Panthenol), Peppermint Oil for scalp circulation, Castor Oil, Argan Oil, Black Currant Seed Oil, and a full botanical aromatic complex. It is also sulfate-free, paraben-free, and handmade in the United States.

The viral shampoo started the conversation. The Just Nutritive formula is built for people who want to go deeper.

Is the Trend a Fad or Something Real?

The ingredients at the center of this trend, onion and rosemary, have been used in Ayurvedic and Mediterranean hair traditions for centuries before TikTok existed. The sulfur in onion genuinely connects to keratin production. The rosemary-DHT inhibition research is peer-reviewed and published. TikTok accelerated awareness of something that traditional herbalists had observed for generations.

What TikTok cannot give you is a properly formulated product. Raw onion juice from the produce drawer brings the smell, the scalp irritation risk, and none of the refinement that makes the active compounds more effective and easier to use consistently. The trend is pointing people in a real direction. A formulated shampoo is how you actually get there.

Frequently Asked Questions

Q: Does onion shampoo actually work for hair growth?

A: There is legitimate scientific interest in onion extract for hair health, rooted in its high sulfur content and keratin-supporting properties. A 2002 peer-reviewed clinical study found 86.9% hair regrowth in patients with patchy alopecia areata after six weeks of topical onion juice use. Rosemary oil, a key co-ingredient, has a 2015 randomized comparative trial showing comparable results to minoxidil 2% over six months in patients with androgenetic alopecia. Results require consistent use over 8 to 12 weeks for meaningful evaluation.

Q: How is the Just Nutritive Onion and Rosemary Shampoo different from the Natural Sant shampoo that went viral on TikTok?

A: The Just Nutritive formula goes beyond the onion and rosemary pairing with a 20-plus ingredient formula that adds three natural DHT blockers (Tea Tree Oil, Nettle Extract, Cedarwood Oil), a strengthening protein complex (Hydrolyzed Soy Protein, Rice Protein, Panthenol B5), Peppermint Oil for scalp stimulation, and botanical oils including Argan, Castor, and Black Currant. It is sulfate-free, paraben-free, and handmade in the USA.