Acne spots appear in areas of skin that have a large number of sebaceous glands. They appear most often on the face, but can also form in other places such as the neck, shoulders, behind the ears, on the chest, on the buttocks and on the upper back.

Acne consists of several different types of spot, which can be roughly divided as follows:
- Blackheads tiny dark coloured blocked pores. The black of the blackheads is due to skin pigment, not dirt.
- Whiteheads - small, firm bumps with a white centre.
- Pustules - pus-filled spots with an obvious balloon of white pus, which may turn yellow as the spot begins to heal.
- Nodules - hard lumps under the skin that can be very painful, go deep into the skin and often cause scars. These are the most common type of spot found in very severe acne, and they often run together in groups. When they heal, they may leave scars.

Acne that  begins at puberty is the result of increased sensitivity to the hormone testosterone, which is present in both boys and girls. Testosterone causes excessive sebum to be secreted from the skins sebaceous glands. Skin cells rapidly divide and sometimes block the opening of hair follicles. The result is a build up of sebum behind the blockage causing the production of blackheads and whiteheads. 

At puberty changes in skin acid levels also encourage the growth of bacterium, which can become trapped in the hair follicles. This produces a deeper infection, in the form of pustules and nodules. 

Other causes:
- Acne sometimes seems to run in families, so there may be a genetic factor that makes certain people more likely to have it.
- Acne may become worse in times of stress, although it is not clear why. It may be because stressed people touch their faces more, spreading the bacteria, or because they are sweating more.
- In girls, outbreaks may be affected by the hormonal changes that occur during the menstrual cycle.
- Another cause may be excessive production of androgens (hormones like testosterone), resulting not from puberty but from conditions such as polycystic ovary syndrome (PCOS).
- Certain drugs such as corticosteroids, anti-epileptic medicines like phenytoin, and oral contraceptives containing levonorgestrel or norethisterone, may aggravate acne.
- Anabolic steroids, sometimes used by body-builders, can cause acne as a side-effect.
- Exposure to dangerous chemicals called dioxins can cause a rare form of acne called chloracne.

Eating greasy foods or chocolate does not cause acne. Having poor hygiene is also not a direct cause, although if you do not wash your face or remove make-up, bacteria will be able to multiply on your skin.

Acne can initially be diagnosed by the appearance of your skin. Spots or blackheads on your face, chest and back are an indication of acne. 

The number of spots, and how painful and inflamed they are, will help your GP assess how severe the condition is. It may be helpful to remove any make-up such as foundation or concealer, so that your doctor can see your skin properly.

The GP will then discuss with you the history of your symptoms, and any previous treatments used, including over-the-counter products. You may also want to discuss the psychological effects of having acne and whether it makes you feel upset or embarrassed.

The type of treatment for acne depends on how severe it is, and whether it is inflammatory (whether the spots are red swollen bumps). 
Treatments availble from Treat Discreet are listed below: 
- Freederm Gel 
- Quinoderm
- Panoxyl Aquagel
- Panoxyl Acne Gel

Mild Acne
Mild non-inflammatory acne (whiteheads and blackheads) may be treated with gels, creams or lotions that are applied directly to the skin (topical). These treatments are available over-the-counter and include:
- retinoids, which contain vitamin A and loosen skin cells that are sealing the hair follicles,
- adapalene, which affects the growth of skin cells or
- benzoyl peroxide, which has antibacterial properties. 
Your pharmacist will be able to give you advise on what treatment is best for you.

Mild to moderate acne
Mild to moderate inflammatory acne (with some pustules and nodules) is often treated with gels, creams or lotions containing:
- benzoyl peroxide,
- azelaic acid, which stops the growth of skin bacteria keeping skin pores clear, or
- topical antibiotics such as clindamycin, which fight bacteria and reduce inflammation. 

Moderate acne
Moderate acne is often successfully treated with a low-dose oral antibiotic, such as tetracycline or erythromycin. These reduce the number of bacteria, inflammation and sebum production. It sometimes takes up to eight weeks for any noticeable improvement and the treatment is usually needed for at least six months.
For women, taking a high oestrogen contraceptive pill may also help acne, by regulating the hormones that cause excess sebum production.

Severe acne. 
If the acne is severe, a dermatologist (skin specialist) may prescribe isotretinoin, a retinoid taken by mouth that acts to loosen excess skin cells and reduce sebum secretion. Clindamycin can also be used to treat more severe cases of acne.

If acne has already left noticeable scars, a cosmetic surgeon may discuss techniques such as dermabrasion or laser treatment. In these procedures, the top layer of skin is removed under a general anaesthetic, leaving a more even layer of skin. There is limited clinical evidence about the effectiveness of these treatments.
Treatment should also help address some of the psychological issues associated with acne, for example by reassuring the person that some of the myths are not true. Acne is not caused by poor hygiene, poor diet or lack of exercise, and is not infectious.