Acne is the inflammation of the oil glands of the skin. The oil glands of the skin are known as sebaceous glands and produce sebum. The glands vary in size during life and become enlarged during teenage years with the onset of puberty.
Posted 16/4/2020 Dr James Britton - Consultant Dermatologist
The production of sebum is under the control of the male sex hormones particularly testosterone in males. The exact link with hormones in females is not as clear, though females have some of these androgens (male hormones) naturally, though at low levels.
The sebaceous gland secretes sebum into the hair follicle and the sebum then passes out through the duct to the surface of the skin, keeping the skin supple. The sebum also has antibacterial properties keeping the numbers of harmful bacteria low.
The sebaceous glands are found on the face, back and chest which are the areas that acne is found. So what happens to cause acne? There are four components....
Increased sebum production
Those who suffer with acne on average secrete more sebum than those who do not have acne and the more sebum that is excreted the more severe the acne can be.  This is controlled by the androgenetic hormones, which includes testosterone. So, if there are increased levels of testosterone then more sebum is excreted possibly leading to acne. This is the case in certain diseases where testosterone is produced, however this is not the case in normal teenage acne.
The theory is that the sebum glands of those who suffer with acne are more sensitive to the hormones and secrete more sebum than they should. Producing more sebum is NOT due to eating fatty foods. This excess production of sebum is caused by the genes of the person, in other words, the way someone is made.
Blockage of the duct
The duct of the oil gland becomes blocked in those who suffer with acne. This is called ductal hypercornification. This leads to the production of comedones which are otherwise known as blackheads and whiteheads. The more comedones a person has the more severe the acne can be.  This can be regarded as causing “blockage” of the duct so the sebum does not flow freely out of the duct.
Blackheads are NOT caused by not cleaning or washing enough or being dirty and the black discolouration is caused by the sebum being oxidised. Scrubbing and scouring the skin will not stop or clear blackheads and can cause problems in itself.
Acne is NOT infectious and cannot be passed on from one person to another. However, it is noted that bacteria are involved with the cause of acne, but not the types of bacteria that cause boils, impetigo or wound infections. The bacteria linked with causing acne is called Propionibacterium acnes (P.Acnes) and colonises the sebum in the sebaceous glands and ducts .
The exact cause of the inflammation in acne is not known but it is possible that it is the chemicals that are made by the p.acnes that cause the immune system to cause excessive inflammation.
Why do certain people get acne?
It is all about how you are made. In those people who have acne, one or more of their parents is most likely to have had acne. This indicates the genetic cause of the condition. The exact genes that are linked with acne are not known and it is likely to be a combination of a few different types of genes that are inherited from an individual’s parents. 
Acne, known as acne vulgaris is a common problem faced by adolescents. Up to 95% of boys and 85% of teenage girls experience a degree of acne with milder spots. Approximately 15% of teenagers suffer from more significant acne that may
cause scarring. This may leave marks on the skin and also affecting sufferers emotionally, requiring the help of a doctor.
Acne in teenage girls versus boys
Acne starts earlier in girls than in boys.
In females acne usually starts between 14 and 17 years with the worst acne during this time and after 17 years it will be improving by itself.
In males the acne usually starts between 16 and 19 years old with the worst acne occurring during this time. It also improves after this time naturally .
Acne persisting after teenage years
Acne improves and clears towards the end of teenage years, but in some it may go on to the mid twenties [5,6]. Acne can persist for several years and approximately 7% of people aged 28 – 40 years are affected, particularly women. In some people for reasons that are not fully understood the acne can develop for the first time after the age of 25.
Younger onset acne
In some children as young as 8 years old the first signs of acne may appear, such as the red papules, comedones (blackheads and whiteheads). Treatment may be required at this stage depending on the degree af scarring and how the person is affected emotionally by the acne.
Onset of acne in infants
New born infants may develop acne from 3 to 24 months of age. This is usually localised to the cheeks with the red papules, some larger nodules and sometimes scarring occurring. This can persist to the age of 5 years old. The exact cause of this is not known but it is thought that the hormones may be affecting the sebaceous glands. 
Can a bad diet cause acne?
It is simply not true that a fatty diet, chocolate or other food items cause acne.
However, the quality of your diet may affect the health of your skin as a whole.
A balanced diet will ensure that your body, including your skin, is getting all the nutrients it needs to be as healthy as possible.
Learn about a balanced diet
There has been suggestions that taking certain vitamins and/or minerals can help to prevent or treat acne. The most common ones you might hear about are Vitamin A, Vitamin E, Selenium and Zinc.
Although some medications for acne contain some of these or are based on substances like them, there is no evidence (as yet) that taking these extra vitamins will help, if taken in larger quantities than what we’d get from a balanced diet.
In fact, these vitamins and minerals can be harmful in large doses.
Always seek advice before supplementing your diet with vitamins and minerals and never take more than the recommended dose suggested on the packet.
Treatments for acne and acne scarring
Treatments for acne depend on how much scarring of the skin is being caused by the acne and also how much the person is affected by the acne. The doctor has to establish both of these facts as the treatments for acne are long term and need
commitment from both the doctor and patient. Acne can cause psychological suffering which does not necessarily reflect the acne severity.
Treatment of acne, even if it is mild, is therefore important as a person may be greatly affected by mild acne whereas another person who has very severe acne may not be self conscious at all.
This is very much down to the individual as the face is particularly sensitive an area to be affected during teenage years. Acne can lead to reduced confidence and low self esteem and this should be recognised by healthcare professionals.
The treatments of acne have the following actions:
reduce sebum production
The keratolytics reduce the blockage in the duct of the hair and sebaceous gland allowing the sebum to flow more freely out of the gland.
The antibacterial treatments can be applied topically or as antibiotics taken by mouth. They reduce the amount of bacteria in the sebaceous glands thereby reducing the amount of chemicals that they produce that can cause inflammation.
The anti- inflammatory treatments reduce the amount of inflammation directly.
No topical treatments reduce the amount of sebum produced, but isotretinoin which is a systemic treatment is very effective at doing this.
Treatments for scarring
The physical scarring that is caused by acne can be red or purple in colour and be raised or leave deep pock marks. The scars improve with time over a period of 18 months or more with them becoming flatter and the colour returning to the normal skin colour.
Laser treatments, dermabrasion, chemical peels and other treatments have been suggested for acne scarring though none has the ability to remove all traces of scarring and their effect is very hard to measure.
Useful websites for acne
 Pochi PE, Strauss JS Sebum production, causal sebum levels, titratable acidity of sebum and urinal fractional 17- ketosteroid excretion in males with acne. J Invest Dermatol.1964; 43: 383- 8
 Holmes RL, Wiliams M, Cunliffe WJ Pilo- sebaceous duct obstruction and acne.Br J Dermatol. 1972; 87: 327- 32
 Marples RR The microflora of the face and acne lesions. J invest Dermatol. 1974;62:326- 31
 Webster GF. Inflammation in acne vulgaris. J Am Acad Dermatol 1995; 33:247- 53
 Burton JL, Cunliffe W J, Stafford et al,, The prevalence of acne vulgaris in adolescence. Br J Dermatol 1971; 85: 119- 26
 Bessone . L’eruzione acneiforme corticotropane e cortisonica cell infanzia. Chron Dermatol 1974;1:77
If you need an opinion and treatment plan for any skin condition that you think may be acne then you can register at www.MyHealthFile.me and upload your pictures and history. A specialist dermatologist will give you a reply within 24 hours.