Sebum production is controlled by our hormones, so a sudden surge in scalp oil production could be down to hormonal changes. If you've recently gone through a major life event that's known to have an impact on your hormone levels, this may be having a knock-on effect on the amount of sebum your scalp is producing.
Hair and puberty
These are both likely caused by the sex hormone testosterone, which is a major player in both female and male reproductive development. Testosterone is thought to increase the production of sebum which is the substance that can make both skin and hair feel oily.
Men have an increase in testosterone, and women produce more estrogen. The increase in hormones can stimulate the production of oil from the sebaceous glands, which may result in oily hair.
Not Getting Enough B Vitamins
"A sufficient intake of the B vitamins, particularly of vitamin B2 (riboflavin) and vitamin B6 (pyridoxine), can help combat greasy hair by regulating sebum production," the site explained.
"As the estrogen levels fall after ovulation, there is a relative excess of androgen hormones causing increased oil production, clogged pores and growth of bacteria," Weiser told SELF.
Those with fine or thin hair, however, may find their hair looks greasy after just one day. It's all to do with the amount of oil your scalp produces, as well as how well your hair can carry that oil.
Oil can build up to a visible level in less than a 24-hour time span. Sometimes intense exercise, overuse of hair products, or even going outside in excessive humidity or heat can trigger an oily hair day.
But you can train your hair to be less oily with a technique called hair training. This involves slowly reducing the frequency of hair washes to get your scalp used to not being rinsed often, naturally minimizing oil production.
Modern lifestyles have led to an increase in anxiety and stress levels, making them one of the most common causes of oily hair. “Stress causes your cortisol levels to rise. Cortisol stresses out the oil glands to produce more sebum, naturally leading to oily hair,” explains Sethi.
"You can train your scalp to be less greasy in the course of three to four days, however, it will take some time for your body to fully adjust," Potempa says. "Take some time to do research about the type of hair you have and establish a new routine that gives your body enough time to adjust to the change."
People with oily hair or who use hair care products daily should consider washing their hair once every 1–2 days. People with dry hair can wash their hair less frequently. Those with textured or coily hair should only wash it once every 1–2 weeks.
The hair cycle and hair follicle structure are highly affected by various hormones. Androgens—such as testosterone (T); dihydrotestosterone (DHT); and their prohormones, dehydroepiandrosterone sulfate (DHEAS) and androstendione (A)—are the key factors in terminal hair growth.
Polycystic ovary syndrome (PCOS), a common hormonal disorder that affects women's reproductive systems, features hyperandrogenism (higher-than-normal androgen levels). PCOS-affected individuals often suffer from an oily scalp and increased hair shedding.
Greasy hair after washing may be due to a person's hair care routine, an overproduction of sebum, environmental factors, or underlying health conditions. People may be able to stop hair from becoming greasy as quickly by using a gentle clarifying shampoo and lightweight, non-greasy hair products.
Vitamin D deficiency: Vitamin D is responsible for regulating the sebum content in the body. A deficiency could lead to an imbalance in our scalp oil levels. Humid climate: The production of sebum touches an all time high in humid conditions.
Overwashing Your Hair
It's not your imagination—the more you wash your hair, the quicker it may seem to need another wash. If you rinse your hair of its natural oils too frequently, it could be trying to overcompensate. Your scalp could be amping up oil production, which means greasier strands in record time.
Apply apple cider vinegar
Yes, the cooking staple can now be used to de-slick your greasy hair, too. “Apple cider vinegar has astringent properties that help remove excess oil from the skin,” says Joshua Zeichner, MD, director of cosmetic and clinical research in dermatology at Mount Sinai Hospital in New York.
Science supports the use of apple cider vinegar as a hair rinse. It could help strengthen hair and improve luster by lowering hair and scalp pH. It may also keep pesky scalp infections and itchiness at bay.
Androgens are the hormones mostly responsible for oil production, and sometimes they can fluctuate, stimulating an increase in sebum production. This often happens during puberty, just before menstruation, during pregnancy and during menopause.