Blackheads are a feature of acne, a common skin condition that involves lesions frequently referred to as pimples, spots, zits, whiteheads or blackheads. Blackheads are a specific kind of dark acne lesion, so-called because they contain oxidized melanin, the pigment made by skin cells called melanocytes.
The reasons for the development of blackheads and the best strategies against them are not well known, but answers can be found in the easy-to-understand information in this article.
Other features of acne are also briefly discussed here, and you can find more detail on separate pages by looking out for relevant links throughout this article.
Contents of this article:
Look out for introductions at the end of some sections to recent developments that have been covered by MNT's news stories.
Here are some key points about blackheads. More detail and supporting information is in the body of this article.
- Blackheads form as a result of excess sebum produced at the base of hairs, often as a result of hormone changes, especially during puberty.
- Sebum contains a dark pigment, melanin, which oxidizes and turns black when exposed to the air; this is why blackheads have a dark appearance.
- A number of persistent myths circulate about the causes of acne, the most outlandish of which is to link it with sexual activity.
- Another myth concerns treatment, saying that "popping" blackheads is helpful - instead, this can worsen the problem and cause scarring.
- There is some evidence that blackheads are more likely to arise when poor diet or disease leads to increased insulin levels, increased levels of IGF-1 and rapid growth of skin cells that lead to clogged pores.
- Blackheads are also known as open comedones and are considered a mild form of acne unless accompanied by more severe types of acne lesions.
- Simple blackheads do not normally cause pain or other symptoms, but the development of more severe acne can result in such symptoms, along with social and psychological effects.
- Medical diagnosis involves physical examination to assess the number and severity of lesions. The psychological impact is also considered, especially for more severe acne.
- Treatment of blackheads themselves is largely a question of self-management but can also involve prescription medications for better effect.
- The help of a doctor is needed if blackheads form part of more problematic acne involving inflammatory lesions.
- Some cases of acne are largely unavoidable, with many risk factors unable to to modified (such as genetics). However, certain steps can be taken to minimize risk and reduce symptoms.
What are blackheads?
Blackheads are a symptom of acne, a skin condition in which the pores of the skin become blocked.1
The pores of the skin are known physiologically as pilosebaceous units - the hair follicles and their accompanying sebaceous glands, which secrete the oily substance sebum.1-4
Sebum has a protective role in the skin, helping to keep it supple and hydrated. When sebum is overproduced, however, it can form plugs in the pores by clumping with epidermal cells that shed from the skin.
The plugs are known as comedones, with black-headed comedones known as open comedones; white-headed comedones (so-called whiteheads) are known as closed comedones. Blackheads are open to the air; the plug turns black because the sebum becomes oxidized, whereas whiteheads are not open to the air.1-4
Comedones fall into one of three groups of acne lesion:1,4,5
- Comedones - blackheads and whiteheads (noninflammatory acne)
- Pustules (inflamed pimples with pus) and papules or nodules (deeper inflamed lesions that may be hard and painful and can involve more than one hair follicle)
- Cysts (large nodules).
Causes of blackheads
Excess production of sebum in hair follicles can lead to the production of blackheads.
Blackheads have a well-described pathogenesis - pores become blocked through the following process:1-4,6
- The sebaceous glands overproduce sebum (and skin cell overgrowth may also be a factor)
- The excess sebum clumps together with dead skin cells and blocks the hair follicle (the base and canal in the skin from which a hair grows)
- The open comedone exposes this plug of sebum to the air, resulting in oxidation of the oily, waxy substance, turning it a black color.
As laid out above, blackheads are a result of abnormal sebum secretion, often combined with overgrowth of skin cells, resulting in blocked pores. While we understand this process, the reasons for excess sebum production are less clear.
Hormonal change during puberty is the most common trigger for excess sebum production. Less common are changes due to menstrual periods, pregnancy and birth control pills.1,5
The male sex hormone androgen triggers greater secretion of sebum and higher turnover of skin cells, and its production surges in both boys and girls during adolescence.1,5
An excess of androgen hormones in adult women may increase the risk of blackheads and other forms of acne, as well as hirsutism (excessive hair growth). Androgen disorders are also linked to polycystic ovarian syndrome (PCOS), with some evidence that acne is more likely in people with PCOS. 15
Other factors involved in acne and the formation of blackheads include:1,5
- Cosmetics, cleansers and clothing that block or cover pores
- Heavy sweating or high humidity
- Dietary factors, disease or medications that encourage rapid skin cell turnover.
Some steroid drugs make acne worse or cause similar skin eruptions.1,5
Does poor hygiene cause blackheads?
There are many myths regarding the causes of acne. The condition is wrongly blamed on factors that research has found no link with. In general, blackheads, and acne as a whole, are not caused by:1,4,5,7
- Poor hygiene or inadequate face washing (excessive washing or scrubbing is likely to make blackheads worse)
- Chocolate, nuts or greasy foods (although there are links in some people to dairy consumption, high glycemic index (GI) diets and diets high in pro-inflammatory animal products)
- Masturbation or sex - an urban myth with no observed links or scientific basis.
On the next page, we look at the symptoms of blackheads and the diagnosis. On the final page, we discuss treatments and prevention of blackheads.