Acne
Acne vulgaris is a common condition in young people. Although it may sometimes be unsightly and can persist for several years, it is not usually serious and resolves in most patients by the age of 25. However, it can have a significant psychological impact as it affects young people at a stage in their lives when they are especially sensitive about their appearance.
Effective treatments for milder forms of acne are available from pharmacies without prescription.
Causes
Acne vulgaris is the result of several factors combined. The condition arises in the pilosebaceous units in the dermis, which consist of a hair follicle and associated sebaceous gland. These glands secrete sebum, a mixture of fats and waxes that protect the skin and hair by retarding water loss and forming a barrier against external agents. The hair follicle is lined with epithelial cells that become keratinised as they mature.
The main processes involved in acne are:
During puberty the production of androgenic hormones increases in both sexes and testosterone levels rise. Testosterone is taken up into the sebaceous glands where it is converted into dihydrotestosterone, which stimulates the glands to secrete increased sebum.
At the same time, keratin in the follicular epithelial wall becomes unusually cohesive and sebum accumulates to form keratin plugs. These block the follicle openings in the epidermis and cause them to dilate beneath the skin surface.
If the orifice of the follicular canal opens sufficiently, the keratinous material extrudes through it and an open comedone results. This is also known as a blackhead, as the keratinous material darkens in contact with the air. Because this material can escape, the comedone does not become inflamed. If the follicular orifice does not open sufficiently, a closed comedone (whitehead) results, within which inflammation can occur. Most acne sufferers have a combination of both.
Microorganisms, mainly Propionibacterium acnes, cause the follicular wall of closed comedones to disrupt and collapse, spilling their contents into the surrounding tissue and provoking an inflammatory response. In addition, bacterial enzymes decompose triglycerides in the sebum to produce free fatty acids, which also cause inflammation. This process leads to the formation of papules around the follicular openings in the more common, milder form of acne
and to cyst formation in the deeper layers of the skin in the more severe form.
Epidemiology
Acne affects approximately 80% of people aged 11–30 years at some time, with about 60% of those sufficiently affected to seek treatment.
Peak incidence is 14–17 years in females and 16–19 years in males.
The condition normally resolves within 10 years of onset, but up to 5% of women and 1% of men may suffer into their 30s.
The incidence of acne appears to have fallen in recent years; the reasons are unknown.
Signs and symptoms
Distribution: lesions usually occur on the forehead, nose and chin, but the periorbital area is usually spared. In more severe cases, the whole of the face, upper chest and back may be affected.
Severity: acne vulgaris is classified according to its clinical features:
Mild: any or all of the following may be present:
• small, tender, red papules
• pustules
• blackheads (small dark plugs of sebum and keratinised epithelial cells)
• whiteheads (small keratin cysts appearing as white papules).
– Moderate: more frequent papules and pustules, with possibly some scarring
– Severe: nodular abscesses, leading to extensive scarring.
Differential diagnosis
Rosacea, an inflammatory skin condition causing acne-like papules and pustules. However, there are also redness and flushing of the central facial area and cheeks. The condition usually occurs in young to early middle-aged adults.
Circumstances for referral
moderate or severe acne
mild acne, if there is no improvement after 2 months with over-the-counter treatment
acne beginning or persisting outside the normal age range for the condition
(teenage years and early 20s)
suspected drug-induced acne: acne is a possible side effect of lithium, phenytoin, progestogens, azathioprine and rifampicin
suspected occupational causes: frequent or prolonged contact with grease and oils may predispose to acne
suspected rosacea.
Treatment
Non-prescription topical treatments are usually the first line of treatment
for mild to moderate acne. Their overall aim is to remove follicular plugs to allow sebum to flow freely, and to minimise bacterial colonisation of the skin.
Treatments must be used regularly for up to 3 months to produce benefits.
Types of preparation available are: keratolytics, antimicrobials, anti- inflammatory agents and abrasive products.
Keratolytics
Keratolytic agents (also known as comedolytics in relation to acne) promote shedding of the keratinised epithelial cells on the skin surface, although the compounds used may do this via different mechanisms.
Keratolytics prevent closure of the pilosebaceous orifice and the formation of follicular plugs, and facilitate sebum flow. They also possess varying levels of antimicrobial activity, which contribute to their effectiveness.
The keratolytic compounds in over-the-counter acne products are benzoyl peroxide, salicylic acid, sulphur and resorcinol.
Benzoyl peroxide
Benzoyl peroxide is generally accepted as the first-line topical treatment for mild to moderate acne.
It is thought to be both comedolytic, mainly through an irritant effect leading to increased turnover of the follicular epithelial cells and increased sloughing, and bactericidal against P. acnes. Benzoyl peroxide is lipophilic and penetrates the follicle well; once absorbed it releases oxygen, which suppresses the bacteria, and reduces the production of irritant free fatty acids.
Benzoyl peroxide is mildly irritant and may cause redness, stinging and peeling, especially at the start of treatment, but tolerance usually develops with continued use. To minimise these effects, the lowest available strength (usually
5%, but 2.5% is available for highly sensitive skin) should be used and applied at night for the first week so that any erythema subsides by the next morning.
If there is no adverse reaction, frequency of application may then be increased to twice daily. Several weeks of regular application are usually required to produce real benefit. If the lower strength is ineffective, the higher strength (10%) can be tried.
Treatment should not continue beyond 3 months with the 5% preparations or beyond 2 months for 10%. If skin irritation is troublesome the product should be stopped for a day or two, and if there is the same reaction when the product is used again it should be discontinued.
Care should be taken to keep all keratolytics away from the eyes, mouth and other mucous membranes. Benzoyl peroxide is an oxidising agent and may bleach clothing and bedclothes.
Benzoyl peroxide is available as creams, lotions, gels and washes (2.5, 5 and
10%, and a 4% cream). There is little difference in clinical response to these concentrations in terms of reducing the number of inflammatory lesions, but formulation appears to make a difference. The drying effect of an alcoholic gel base enhances the effectiveness of the active constituent, and it is more
effective than a lotion of the same concentration. However, gels have a greater potential for causing skin dryness and irritation than preparations in aqueous bland bases, so water-based preparations may improve compliance.
Salicylic acid
Salicylic acid is used in concentrations of up to 2% for acne.
It exerts its keratolytic effect by increasing the hydration of epithelial cells.
It may also have some bacteriostatic activity and a direct anti-inflammatory effect on lesions. It is believed to enhance penetration into the skin of
other medicaments, and is combined with sulphur in some formulary preparations.
Salicylic acid is a mild irritant and similar precautions should be adopted
as for benzoyl peroxide. Preparations are applied twice or three times a day. Salicylic acid is readily absorbed through the skin and excreted slowly, and salicylate poisoning can occur if preparations are applied frequently, in large amounts and over large areas. Patients who are sensitive to aspirin should avoid these preparations.
Sulphur and resorcinol
Sulphur and resorcinol are claimed to possess keratolytic and antiseptic properties, but this is debatable and there is little evidence of effectiveness. Both can cause skin irritation and sensitisation, and resorcinol can cause other adverse effects. Both substances are now little used.
Antimicrobials
Antimicrobial compounds available in over-the-counter preparations are cetrimide, chlorhexidine, povidone-iodine, triclocarban and triclosan.
As two of the contributory factors to acne are increased sebum production and P. acnes, one approach to treatment is to remove excess sebum from the skin and reduce the bacterial count. To this end, several products are formulated
as astringent lotions and detergent-based washes containing antibacterial or antiseptic ingredients, and there are also some antimicrobial creams.
Abrasives
There is one product containing an abrasive licensed for acne treatment. It contains small, gritty particles in a skin wash, intended to remove follicular plugs mechanically. It is contraindicated in the presence of superficial venules or capillaries (telangiectasia), and overenthusiastic use can cause irritation. There is little evidence of the effectiveness of abrasive preparations in acne.
Anti-inflammatory
Topical nicotinamide is claimed to have anti-inflammatory activity. It appears to be effective. It may produce side-effects of dryness, peeling and irritation similar to those of benzoyl peroxide, and the same precautions in use should be taken.
Prescription treatments
Topical comedolytic, antibacterial and combined comedolytic/antimicrobial preparations.
Oral antibacterials: these can be prescribed if topical therapy alone is ineffective. Tetracycline, oxytetracycline, doxycycline, minocycline, lymecycline, erythromycin and trimethoprim are the agents used. Treatment is long-term – for up to 2 years.
Hormonal treatment: co-cyprindiol, containing cyproterone, an antiandrogen that decreases sebum production, and ethinylestradiol, can be prescribed for women with moderate to severe acne. It also prevents ovulation and, although it is no more effective for acne than oral antibacterials, it is useful for women who also want oral contraception.
Oral isotretinoin is available for severe acne refractive to other forms of treatment. It is effective but is teratogenic and can have severe side-effects. It should be prescribed only by, or under the supervision of, a consultant dermatologist.
Additional advice
There is no evidence that poor hygiene causes acne, but washing the face twice a day with an antibacterial soap or a mild cleanser degreases the skin and removes bacteria, and should help reduce the severity of the condition. Sweat should not be allowed to remain on the skin, but should be washed off as soon as possible.
Avoid hairstyles in which the hair is constantly touching the face, and shampoo hair regularly.
Pimples and blackheads should not be squeezed or pinched with the fingers.
Comedone expressors (blackhead removers) can be used; removal is aided by exposing the skin to steam first.
Natural sunlight is thought to be helpful in reducing acne, but overexposure should be avoided.
Avoid heavy, greasy cosmetics and use water-based moisturisers.
There is no evidence that fatty foods and chocolate cause acne, but no harm is done by seeing if excluding them from the diet has a beneficial effect.
A healthy, balanced diet with plenty of water, and regular exercise, is always
good advice.
Acne vulgaris is a common condition in young people. Although it may sometimes be unsightly and can persist for several years, it is not usually serious and resolves in most patients by the age of 25. However, it can have a significant psychological impact as it affects young people at a stage in their lives when they are especially sensitive about their appearance.
Effective treatments for milder forms of acne are available from pharmacies without prescription.
Causes
Acne vulgaris is the result of several factors combined. The condition arises in the pilosebaceous units in the dermis, which consist of a hair follicle and associated sebaceous gland. These glands secrete sebum, a mixture of fats and waxes that protect the skin and hair by retarding water loss and forming a barrier against external agents. The hair follicle is lined with epithelial cells that become keratinised as they mature.
The main processes involved in acne are:
During puberty the production of androgenic hormones increases in both sexes and testosterone levels rise. Testosterone is taken up into the sebaceous glands where it is converted into dihydrotestosterone, which stimulates the glands to secrete increased sebum.
At the same time, keratin in the follicular epithelial wall becomes unusually cohesive and sebum accumulates to form keratin plugs. These block the follicle openings in the epidermis and cause them to dilate beneath the skin surface.
If the orifice of the follicular canal opens sufficiently, the keratinous material extrudes through it and an open comedone results. This is also known as a blackhead, as the keratinous material darkens in contact with the air. Because this material can escape, the comedone does not become inflamed. If the follicular orifice does not open sufficiently, a closed comedone (whitehead) results, within which inflammation can occur. Most acne sufferers have a combination of both.
Microorganisms, mainly Propionibacterium acnes, cause the follicular wall of closed comedones to disrupt and collapse, spilling their contents into the surrounding tissue and provoking an inflammatory response. In addition, bacterial enzymes decompose triglycerides in the sebum to produce free fatty acids, which also cause inflammation. This process leads to the formation of papules around the follicular openings in the more common, milder form of acne
and to cyst formation in the deeper layers of the skin in the more severe form.
Epidemiology
Acne affects approximately 80% of people aged 11–30 years at some time, with about 60% of those sufficiently affected to seek treatment.
Peak incidence is 14–17 years in females and 16–19 years in males.
The condition normally resolves within 10 years of onset, but up to 5% of women and 1% of men may suffer into their 30s.
The incidence of acne appears to have fallen in recent years; the reasons are unknown.
Signs and symptoms
Distribution: lesions usually occur on the forehead, nose and chin, but the periorbital area is usually spared. In more severe cases, the whole of the face, upper chest and back may be affected.
Severity: acne vulgaris is classified according to its clinical features:
Mild: any or all of the following may be present:
• small, tender, red papules
• pustules
• blackheads (small dark plugs of sebum and keratinised epithelial cells)
• whiteheads (small keratin cysts appearing as white papules).
– Moderate: more frequent papules and pustules, with possibly some scarring
– Severe: nodular abscesses, leading to extensive scarring.
Differential diagnosis
Rosacea, an inflammatory skin condition causing acne-like papules and pustules. However, there are also redness and flushing of the central facial area and cheeks. The condition usually occurs in young to early middle-aged adults.
Circumstances for referral
moderate or severe acne
mild acne, if there is no improvement after 2 months with over-the-counter treatment
acne beginning or persisting outside the normal age range for the condition
(teenage years and early 20s)
suspected drug-induced acne: acne is a possible side effect of lithium, phenytoin, progestogens, azathioprine and rifampicin
suspected occupational causes: frequent or prolonged contact with grease and oils may predispose to acne
suspected rosacea.
Treatment
Non-prescription topical treatments are usually the first line of treatment
for mild to moderate acne. Their overall aim is to remove follicular plugs to allow sebum to flow freely, and to minimise bacterial colonisation of the skin.
Treatments must be used regularly for up to 3 months to produce benefits.
Types of preparation available are: keratolytics, antimicrobials, anti- inflammatory agents and abrasive products.
Keratolytics
Keratolytic agents (also known as comedolytics in relation to acne) promote shedding of the keratinised epithelial cells on the skin surface, although the compounds used may do this via different mechanisms.
Keratolytics prevent closure of the pilosebaceous orifice and the formation of follicular plugs, and facilitate sebum flow. They also possess varying levels of antimicrobial activity, which contribute to their effectiveness.
The keratolytic compounds in over-the-counter acne products are benzoyl peroxide, salicylic acid, sulphur and resorcinol.
Benzoyl peroxide
Benzoyl peroxide is generally accepted as the first-line topical treatment for mild to moderate acne.
It is thought to be both comedolytic, mainly through an irritant effect leading to increased turnover of the follicular epithelial cells and increased sloughing, and bactericidal against P. acnes. Benzoyl peroxide is lipophilic and penetrates the follicle well; once absorbed it releases oxygen, which suppresses the bacteria, and reduces the production of irritant free fatty acids.
Benzoyl peroxide is mildly irritant and may cause redness, stinging and peeling, especially at the start of treatment, but tolerance usually develops with continued use. To minimise these effects, the lowest available strength (usually
5%, but 2.5% is available for highly sensitive skin) should be used and applied at night for the first week so that any erythema subsides by the next morning.
If there is no adverse reaction, frequency of application may then be increased to twice daily. Several weeks of regular application are usually required to produce real benefit. If the lower strength is ineffective, the higher strength (10%) can be tried.
Treatment should not continue beyond 3 months with the 5% preparations or beyond 2 months for 10%. If skin irritation is troublesome the product should be stopped for a day or two, and if there is the same reaction when the product is used again it should be discontinued.
Care should be taken to keep all keratolytics away from the eyes, mouth and other mucous membranes. Benzoyl peroxide is an oxidising agent and may bleach clothing and bedclothes.
Benzoyl peroxide is available as creams, lotions, gels and washes (2.5, 5 and
10%, and a 4% cream). There is little difference in clinical response to these concentrations in terms of reducing the number of inflammatory lesions, but formulation appears to make a difference. The drying effect of an alcoholic gel base enhances the effectiveness of the active constituent, and it is more
effective than a lotion of the same concentration. However, gels have a greater potential for causing skin dryness and irritation than preparations in aqueous bland bases, so water-based preparations may improve compliance.
Salicylic acid
Salicylic acid is used in concentrations of up to 2% for acne.
It exerts its keratolytic effect by increasing the hydration of epithelial cells.
It may also have some bacteriostatic activity and a direct anti-inflammatory effect on lesions. It is believed to enhance penetration into the skin of
other medicaments, and is combined with sulphur in some formulary preparations.
Salicylic acid is a mild irritant and similar precautions should be adopted
as for benzoyl peroxide. Preparations are applied twice or three times a day. Salicylic acid is readily absorbed through the skin and excreted slowly, and salicylate poisoning can occur if preparations are applied frequently, in large amounts and over large areas. Patients who are sensitive to aspirin should avoid these preparations.
Sulphur and resorcinol
Sulphur and resorcinol are claimed to possess keratolytic and antiseptic properties, but this is debatable and there is little evidence of effectiveness. Both can cause skin irritation and sensitisation, and resorcinol can cause other adverse effects. Both substances are now little used.
Antimicrobials
Antimicrobial compounds available in over-the-counter preparations are cetrimide, chlorhexidine, povidone-iodine, triclocarban and triclosan.
As two of the contributory factors to acne are increased sebum production and P. acnes, one approach to treatment is to remove excess sebum from the skin and reduce the bacterial count. To this end, several products are formulated
as astringent lotions and detergent-based washes containing antibacterial or antiseptic ingredients, and there are also some antimicrobial creams.
Abrasives
There is one product containing an abrasive licensed for acne treatment. It contains small, gritty particles in a skin wash, intended to remove follicular plugs mechanically. It is contraindicated in the presence of superficial venules or capillaries (telangiectasia), and overenthusiastic use can cause irritation. There is little evidence of the effectiveness of abrasive preparations in acne.
Anti-inflammatory
Topical nicotinamide is claimed to have anti-inflammatory activity. It appears to be effective. It may produce side-effects of dryness, peeling and irritation similar to those of benzoyl peroxide, and the same precautions in use should be taken.
Prescription treatments
Topical comedolytic, antibacterial and combined comedolytic/antimicrobial preparations.
Oral antibacterials: these can be prescribed if topical therapy alone is ineffective. Tetracycline, oxytetracycline, doxycycline, minocycline, lymecycline, erythromycin and trimethoprim are the agents used. Treatment is long-term – for up to 2 years.
Hormonal treatment: co-cyprindiol, containing cyproterone, an antiandrogen that decreases sebum production, and ethinylestradiol, can be prescribed for women with moderate to severe acne. It also prevents ovulation and, although it is no more effective for acne than oral antibacterials, it is useful for women who also want oral contraception.
Oral isotretinoin is available for severe acne refractive to other forms of treatment. It is effective but is teratogenic and can have severe side-effects. It should be prescribed only by, or under the supervision of, a consultant dermatologist.
Additional advice
There is no evidence that poor hygiene causes acne, but washing the face twice a day with an antibacterial soap or a mild cleanser degreases the skin and removes bacteria, and should help reduce the severity of the condition. Sweat should not be allowed to remain on the skin, but should be washed off as soon as possible.
Avoid hairstyles in which the hair is constantly touching the face, and shampoo hair regularly.
Pimples and blackheads should not be squeezed or pinched with the fingers.
Comedone expressors (blackhead removers) can be used; removal is aided by exposing the skin to steam first.
Natural sunlight is thought to be helpful in reducing acne, but overexposure should be avoided.
Avoid heavy, greasy cosmetics and use water-based moisturisers.
There is no evidence that fatty foods and chocolate cause acne, but no harm is done by seeing if excluding them from the diet has a beneficial effect.
A healthy, balanced diet with plenty of water, and regular exercise, is always
good advice.
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