Acne vulgaris is a disorder of pilosebaceous complex which predominantly affects the peripubertal population

Acne vulgaris ( acne) is a long-term skin disease that occurs when hair follicles become clogged with dead skin cells and oil from the skin

Acne primarily affects skin with a greater number of oil glands, including the face, upper part of the chest, and back. During puberty, in both sexes, acne is often brought on by an increase in androgens such as testosterone. Excessive growth of the bacteria Propionibacterium acnes, which is normally present on the skin, is often involved.

Acne occurs most commonly during adolescence, affecting an estimated 80–90% of teenagers in the Western world.

Classification
Acne is commonly classified by severity as mild, moderate, or severe. This type of categorization can be an important factor in determining the appropriate treatment regimen. Mild acne is classically defined as open (blackheads) and closed comedones (whiteheads) limited to the face with occasional inflammatory lesions. Acne may be considered to be of moderate severity when a higher number of inflammatory papules and pustules occur on the face compared to mild cases of acne, and acne lesions also occur on the trunk of the body. Lastly, severe acne is said to occur when nodules (the painful 'bumps' lying under the skin) are the characteristic facial lesions, and involvement of the trunk is extensive.

Cause

Genetic
The predisposition to acne for specific individuals is likely explained in part by a genetic component,

Hormonal
Hormonal activity, such as occurs during menstrual cycles and puberty, may contribute to the formation of acne. During puberty, an increase in sex hormones called androgens causes the follicular glands to grow larger and make more sebum.

Infectious
Propionibacterium acnes (P. acnes) is the anaerobic bacterium species that is widely suspected to contribute to the development of acne

Diet
The relationship between diet and acne is unclear Additionally, there is weak observational evidence suggesting that dairy milk consumption is positively associated with a higher incidence and severity of acne

Smoking

Cigarette smoking is known to increase the risk of developing acne.Additionally, acne severity worsens as the number of cigarettes per day a person smokes increases.

Psychological
Overall, few high-quality studies have been performed which demonstrate that stress causes or worsens acne. While the connection between acne and stress has been debated, some research indicates that increased acne severity is associated with high stress levels in certain settings (e.g., in association with the hormonal changes seen inpremenstrual syndrome).

Signs and symptoms
Typical features of acne include seborrhea (increased oil secretion), microcomedones, comedones, papules, pustules, nodules (large papules), and in many cases scarring.The appearance of acne varies with skin color. It may result in psychological and social problems.]

Scars
Acne scars are the result of inflammation within the dermal layer of skin, brought on by acne, and are estimated to affect 95% of people with acne vulgaris. Scarring is most likely to occur with severe nodular acne, but may occur with any form of acne vulgaris

Atrophic acne scars are the most common type of acne scar and have lost collagen from this healing response. Atrophic scars may be further classified as ice-pick scars, boxcar scars, and rolling scars. Ice-pick scars are typically described as narrow (less than 2 mm across), deep scars that extend into the dermis. Boxcar scars are round or ovoid indented scars with sharp borders and vary in size from 1.5–4 mm across. Rolling scars are wider than ice-pick and boxcar scars (4–5 mm across) and have a wave-like pattern of depth in the skin.

Hypertrophic scars are less common, and are characterized by increased collagen content after the abnormal healing response.]They are described as firm and raised from the skin.Hypertrophic scars remain within the original margins of the wound, whereas keloid scars can form scar tissue outside of these borders. Keloid scars from acne usually occur in men, and usually occur on the trunk of the body rather than the face.

Pigmentation
Postinflammatory hyperpigmentation (PIH) is usually the result of nodular acne lesions. They often leave behind an inflamed red mark after the original acne lesion has resolved. PIH occurs more often in people with darker skin color.

Treatments
Commonly-used medical treatments include topical therapies such as antibiotics, benzoyl peroxide, and retinoids, and systemic therapies including antibiotics, hormonal agents, and oral retinoids. Procedures such as light therapy and laser therapy are not considered to be first-line treatments and typically have an adjunctive role due to their high cost and the limited evidence of their efficacy.

Benzoyl peroxid
Benzoyl peroxide cream
Benzoyl peroxide is a first-line treatment for mild and moderate acne due to its effectiveness and mild side-effects (mainly irritantdermatitis). It works against P. acnes, helps prevent formation of comedones, and has anti-inflammatory properties.Benzoyl peroxide normally causes dryness of the skin, slight redness, and occasional peeling when side effects occur.

Retinoids
Retinoids are medications which possess anti-inflammatory properties, normalize the follicle cell life cycle, and reduce sebum production.

Antibiotics
Topical antibiotics are frequently used for mild to moderately severe acne.[14] Oral antibiotics are indicated for moderate to severe cases of inflammatory acne, and decrease acne due to their anti-inflammatory properties and antimicrobial activity

Hormonal[edit]
In women, acne can be improved with the use of any combined oral contraceptive.[62] Oral contraceptives decrease the ovaries' production of androgen hormones, resulting in lower skin production of sebum, and consequently improve acne severity

Other medications
Topical and oral preparations of nicotinamide have been suggested as alternative medical treatments for acne.

Combination therapy
Combination therapy — using medications of different classes together, each with a different mechanism of action — has been demonstrated to be a more efficacious approach to acne treatment than monotherapy. The use of topical benzoyl peroxide and antibiotics together has been shown to be more effective than antibiotics alone.

Treatment with homoeopathy
Acne is very well treated with homoeopathy with good result.
The most commonly used medicine for acne are:-
Berberis aquifolium
Sepia
Nat mur
Ant crud
Cimicifuga
Kali br