What Causes Greasy Hair? What the Research Shows

We found no evidence that a vitamin deficiency causes greasy hair. What the research does show is that oily hair reflects high sebum production, which relates to sebaceous gland activity, and that scalp conditions such as dandruff and seborrheic dermatitis involve excess oil, fungal colonization and individual susceptibility.

Here's what the research says about why hair gets greasy, what treatments exist, and when to see a doctor.

I LOVE MY HAIR NOW

FullyVital hair serum and hair vitamins made tremendous improvements in my hair. I truly love my hair now.

Dorit S.,

Shop Hair Products

Key Takeaways

• Oily skin and hair have high sebum values that correlate with sebaceous gland activity and with porphyrin counts.
• Dandruff and seborrheic dermatitis involve sebaceous secretions, skin-surface fungal colonization and individual susceptibility.
• In a randomized trial of people with an oily scalp, one session of botulinum toxin injections reduced scalp sebum for about 3 months. It's a medical procedure.
• We found no study linking a vitamin deficiency to greasy hair.

What Makes Hair Greasy?

Sebum is the oil made by the sebaceous glands in your scalp. When there's more of it, hair looks greasy faster after washing. How much you make varies from person to person.

Is It A Vitamin Deficiency?

We didn't find research showing that. If you have other symptoms, such as flaking, redness or hair loss, a doctor can check for causes, including nutrient deficiencies.

Our Best Sellers

3-Month Growth Bundle

$269.00

Shop Hair System

Hair Revival Supplements

$47.20

Shop Vitamins

What To Do

• Wash regularly with a gentle shampoo.
• See a dermatologist if your scalp is itchy, flaky or red, or if you're also losing hair.
• Don't assume supplements will fix oil. There's no evidence they do.

Our Best Sellers

3-Month Growth Bundle

$269.00

Shop Hair System

Hair Revival Serum

$47.20

Shop Hair Serum

What The Research Shows

Sebum And The Scalp

In 100 women, oily skin and hair showed high sebum values that correlated with porphyrin counts and the activity of sebaceous glands. Formulations containing a guarana extract reduced sebum on the face and scalp two hours after application (Gabarra Almeida Leite & Maia Campos, 2020).

Dandruff And Seborrheic Dermatitis

Dandruff is restricted to the scalp and involves itchy, flaking skin without visible inflammation. Seborrheic dermatitis can also affect other oily areas and involves inflammation. Sebaceous secretions, skin-surface fungal colonization, individual susceptibility and the interactions among them all contribute (Borda & Wikramanayake, 2015).

A Medical Treatment For Oily Scalp

In a multicenter, randomized, double-blind trial, 49 people with an oily scalp received a single session of intradermal botulinum toxin A (50 to 65 U) or saline. The botulinum toxin group had significantly less scalp sebum at the 1- and 3-month visits and higher satisfaction, with no serious adverse events. The effect wasn't significant at 4 and 6 months (Li et al., 2023). It's an injection given by a clinician.

Scalp oil is sometimes linked with blocked follicles; see our article on clogged hair follicles.

For shampoo choices, see our article on oily hair shampoo.

See also: Scalp Detox: What the Research Shows

Frequently Asked Questions

Can a vitamin deficiency cause greasy hair?

We found no study showing that.

Why does my hair get greasy so fast?

Oily hair reflects high sebum production and sebaceous gland activity. Scalp conditions like dandruff and seborrheic dermatitis also involve excess oil.

How can I reduce oily hair?

Wash regularly with a gentle shampoo, and see a dermatologist if you have flaking, redness or itch.

References

1. Gabarra Almeida Leite M, Maia Campos PMBG. Correlations between sebaceous glands activity and porphyrins in the oily skin and hair and immediate effects of dermocosmetic formulations. J Cosmet Dermatol. 2020. PubMed
2. Borda LJ, Wikramanayake TC. Seborrheic Dermatitis and Dandruff: A Comprehensive Review. J Clin Investig Dermatol. 2015. PubMed
3. Li Y, Chen X, Luo X, et al. Intradermal Botulinum Toxin A Injection for Scalp Sebum Secretion Regulation: A Multicenter, Randomized, Double-Blinded, Placebo-Controlled, Prospective Study in Chinese Subjects. Aesthet Surg J. 2023. PubMed