Terminology
Different types of Acne Vulgaris: A: Cystic acne on
the face, B: Subsiding tropical acne of trunk, C:
Extensive acne on chest and shoulders.
The term acne comes from a corruption of the
Greek άκμή (acne in the sense of a skin eruption) in
the writings of
Aëtius Amidenus. Used by itself, the term "acne" refers to
the presence of
pustules and
papules.[7]
The most common form of acne is known as "acne vulgaris",
meaning "common acne". Many teenagers get this type of acne. Use
of the term "acne vulgaris" implies the presence of
comedones.[8]
The term "acne rosacea" is a synonym for
rosacea.[9]
Chloracne is associated with
chlorine toxicity.
Causes of acne
Acne develops as a result of blockages in
follicles.
Hyperkeratinization and formation of a plug of
keratin and
sebum (a microcomedo) is the earliest change. Enlargement of
sebaceous glands and an increase in sebum production occur with
increased
androgen (DHEA-S)
production at
adrenarche. The microcomedo may enlarge to form an open
comedo (blackhead)
or closed comedo (whitehead).
Whiteheads are the direct result of
skin
pores becoming clogged with
sebum, a naturally occurring oil, and dead skin cells. In
these conditions the naturally occurring largely commensal
bacteria
Propionibacterium acnes can cause
inflammation, leading to inflammatory lesions (papules,
infected pustules, or nodules) in the
dermis around the microcomedo or comedo, which results in
redness and may result in
scarring or
hyperpigmentation.[10]
Primary causes
The root cause of why some people get acne and some do not is
not fully known. It is known to be partly hereditary. Several
factors are known to be linked to acne:
- Family/Genetic history. The tendency to develop acne
runs in families. For example, school-age boys with acne
often have other members in their family with acne as well.
A family history of acne is associated with an earlier
occurrence of acne and an increased number of retentional
acne lesions.[11]
- Hormonal activity, such as
menstrual cycles and
puberty. During puberty, an increase in male sex
hormones called androgens cause the follicular glands to get
larger and make more sebum.[12]
- Inflammation, skin irritation or scratching of any sort
will activate inflammation. Anti-inflammatories are known to
improve acne[citation
needed].
- Stress, through increased output of hormones from the
adrenal (stress) glands, although modern tests have said
otherwise and point to this not being a cause[citation
needed].
- Hyperactive
sebaceous glands, secondary to the three hormone sources
above.
- Accumulation of dead skin cells that block or cover
pores[citation
needed].
- Bacteria in the
pores. Propionibacterium acnes (P. acnes) is the
anaerobic bacterium that causes acne. In-vitro resistance of
P. acnes to commonly used antibiotics has been increasing.[13]
- Use of
anabolic steroids[citation
needed].
- Any medication containing
lithium,
barbiturates or
androgens.[citation
needed]
- Exposure to certain chemical compounds.
Chloracne is particularly linked to toxic exposure to
dioxins, namely
Chlorinated dioxins[citation
needed].
- Exposure to
halogens. Halogen acne is linked to exposure to halogens
(e.g. iodides, chlorides, bromides, fluorides)[citation
needed].
- Chronic use of
amphetamines or other similar drugs.[14]
Several
hormones have been linked to acne: the androgens
testosterone,
dihydrotestosterone (DHT) and
dehydroepiandrosterone sulfate (DHEAS), as well as
insulin-like growth factor 1 (IGF-I). In addition,
acne-prone skin has been shown to be
insulin resistant[citation
needed].
Development of acne vulgaris in later years is uncommon,
although this is the age group for
Rosacea which may have similar appearances. True acne
vulgaris in adult women may be a feature of an underlying
condition such as pregnancy and disorders such as
polycystic ovary syndrome or the rare
Cushing's syndrome. Menopause-associated acne occurs as
production of the natural anti-acne ovarian hormone
estradiol fails at menopause. The lack of estradiol also
causes thinning hair, hot flashes, thin skin, wrinkles, vaginal
dryness, and predisposes to osteopenia and osteoporosis as well
as triggering acne (known as acne climacterica in this
situation).
Diet
Many patients hold the belief that their acne is influenced
by dietary factors. In the early 1900s, a few doctors discovered
European and traditional diets highly reduced chronic diseases
and acne than US diet. Past doctors advise eating whole, raw
food for optimum health. Most dermatologists today are awaiting
confirmatory research linking diet and acne but some support the
idea that acne sufferers should experiment with their diets, and
refrain from consuming such fare, including chocolate, if they
find such food affects the severity of their acne.
[15]
Milk
Recently, three
epidemiological studies from the same group of scientists
found an association between acne and consumption of partially
skimmed
milk, instant breakfast drink,
sherbet,
cottage cheese, and
cream cheese.[16][17][18]
The researchers hypothesize that the association may be caused
by hormones (such as several sex hormones and bovine
insulin-like growth factor 1 (IGF-1)) or even iodine[19]
present in cow milk.
Carbohydrates
The long-held belief that there is no link between diets high
in refined sugars and processed foods, and acne, has recently
been challenged.[20]
The previous belief was based on earlier studies (some using
chocolate and
Coca Cola) that were methodologically flawed.[20][21][22]
The recent low glycemic-load hypothesis postulates that rapidly
digested carbohydrate foods (such as soft drinks, sweets, white
bread) produce an overload in blood glucose (hyperglycemia)
that stimulates the secretion of
insulin, which in turn triggers the release of
IGF-1.[20]
IGF-1 has direct effects on the pilosebaceous unit (and insulin
at high concentrations can also bind to the IGF-1 receptor)[23]
and has been shown to stimulate
hyperkeratosis and
epidermal
hyperplasia.[24]
These events facilitate acne formation. Sugar consumption might
also influence the activity of
androgens via a decrease in
sex hormone-binding globulin concentration.[25][26]
In support of this hypothesis, a
randomized controlled trial of a low glycemic-load diet
improved acne and reduced weight, androgen activity and levels
of
insulin-like growth factor binding protein-1.[27]
High IGF-1 levels and mild
insulin resistance (which causes higher levels of insulin)
had previously been observed in patients with acne.[28][29][30]
High levels of insulin and acne are also both features of
polycystic ovarian syndrome.[20]
According to this hypothesis, the absence of acne in some
non-Westernized societies could be explained by the low
glycemic index of these cultures' diets.[31]
It is possible that genetic reasons account for there being no
acne in these populations, although similar populations (such as
South American Indians or Pacific Islanders) do develop acne.[32][33]
Note also that the populations studied consumed no milk or other
dairy products.[34]
Further research is necessary to establish whether a reduced
consumption of high-glycemic foods, or treatment that results in
increased insulin sensitivity (like
metformin) can significantly alleviate acne, though
consumption of high-glycemic foods should in any case be kept to
a minimum, for general health reasons.[35]
Avoidance of "junk
food" with its high fat and sugar content is also
recommended.[36]
Vitamins A and E
Studies have shown that newly diagnosed acne patients tend to
have lower levels of
vitamin A circulating in their bloodstream than those who
are acne free.[37]
In addition people with severe acne also tend to have lower
blood levels of
vitamin E.[38]
Hygiene
Acne is not caused by dirt. This misconception probably comes
from the fact that
blackheads look like dirt stuck in the openings of pores.
The black color is not dirt but simply oxidised keratin. In
fact, the blockages of
keratin that cause acne occur deep within the narrow
follicle channel, where it is impossible to wash them away.
These plugs are formed by the failure of the cells lining the
duct to separate and flow to the surface in the sebum created
there by the body. Built-up oil of the skin can block the
passages of these pores, so standard washing of the face could
wash off old oil and help unblock the pores.
Treatments
Available treatments
There are many products available for the treatment of acne,
many of which are without any scientifically-proven effects.
Generally speaking, successful treatments show little
improvement within the first two weeks, instead taking a period
of approximately three months to improve and start flattening
out. Many treatments that promise big improvements within two
weeks are likely to be largely disappointing. However, short
bursts of cortisone can give very quick results, and other
treatments can rapidly improve some active spots, but usually
not all active spots.
Modes of improvement are not necessarily fully understood but
in general treatments are believed to work in at least 4
different ways (with many of the best treatments providing
multiple simultaneous effects):
A combination of treatments can greatly reduce the amount and
severity of acne in many cases. Those treatments that are most
effective tend to have greater potential for side effects and
need a greater degree of monitoring, so a step-wise approach is
often taken. Many people consult with doctors when deciding
which treatments to use, especially when considering using any
treatments in combination. There are a number of treatments that
have been proven effective:
Topical bactericidals
Widely available
OTC bactericidal products containing
benzoyl peroxide may be used in mild to moderate acne. The
gel or cream containing benzoyl peroxide is rubbed, twice daily,
into the pores over the affected region. Bar soaps or washes may
also be used and vary from 2 to 10% in strength. In addition to
its therapeutic effect as a keratolytic (a chemical that
dissolves the keratin plugging the pores) benzoyl peroxide also
prevents new lesions by killing
P. acnes. In one study, roughly 70% of participants
using a 10% benzoyl peroxide solution experienced a reduction in
acne lesions after 6 weeks.[39]Unlike
antibiotics, benzoyl peroxide has the advantage of being a
strong oxidizer (essentially a mild bleach) and thus does not
appear to generate bacterial resistance. However, it routinely
causes dryness, local irritation and redness. A sensible regimen
may include the daily use of low-concentration (2.5%) benzoyl
peroxide preparations, combined with suitable
non-comedogenic moisturisers to help avoid overdrying the
skin.
Care must be taken when using benzoyl peroxide, as it can
very easily bleach any fabric or hair it comes in contact with.
Other antibacterials that have been used include
triclosan, or
chlorhexidine gluconate. Though these treatments are often
less effective, they also have fewer side-effects.
Prescription-strength benzoyl peroxide preparations do not
necessarily differ with regard to the maximum concentration of
the active ingredient (10%), but the drug is made available
dissolved in a vehicle that more deeply penetrates the pores of
the skin.
Topical antibiotics
Externally applied antibiotics such as
erythromycin,
clindamycin,
stievamycin, or
tetracycline kill the bacteria that are harbored in the
blocked follicles. While topical use of antibiotics is equally
as effective as oral use, this method avoids possible side
effects including upset stomach and drug interactions (e.g. it
will not affect use of the oral contraceptive pill), but may
prove awkward to apply over larger areas than just the face
alone.
Oral antibiotics
Oral antibiotics used to treat acne include erythromycin or
one of the
tetracycline antibiotics (tetracycline,
the better absorbed
oxytetracycline, or one of the once daily
doxycycline,
minocycline, or
lymecycline).
Trimethoprim is also sometimes used (off-label
use in UK). However, reducing the P. acnes bacteria
will not, in itself, do anything to reduce the oil secretion and
abnormal cell behaviour that is the initial cause of the blocked
follicles. Additionally the antibiotics are becoming less and
less useful as resistant P. acnes are becoming more
common. Acne will generally reappear quite soon after the end of
treatment—days later in the case of
topical applications, and weeks later in the case of oral
antibiotics. Furthermore side effects of tetracycline
antibiotics can include yellowing of the teeth and an imbalance
of gut flora, so are only recommended after topical products
have been ruled out.
It has been found that sub-antimicrobial doses of antibiotics
such as minocycline also improve acne. It is believed that
minocycline's anti-inflammatory effect also prevents acne. These
low doses do not kill bacteria and hence cannot induce
resistance.
Hormonal treatments
In females, acne can be improved with
hormonal treatments. The common combined
oestrogen/progestogen
methods of
hormonal contraception have some effect, but the
antiandrogen,
Cyproterone, in combination with an oestrogen (Diane 35)
is particularly effective at reducing androgenic hormone levels.
Diane-35 is not available in the USA, but a newer oral
contraceptive containing the progestin
drospirenone is now available with fewer side effects than
Diane 35 / Dianette. Both can be used where blood tests show
abnormally high levels of
androgens, but are effective even when this is not the case.
Along with this, treatment with low dose spironolactone can have
anti-androgenetic properties, especially in patients with
polycystic ovarian syndrome.
If a pimple is large and/or does not seem to be affected by
other treatments, a dermatologist may administer an injection of
cortisone directly into it, which will usually reduce
redness and inflammation almost immediately. This has the effect
of flattening the pimple, thereby making it easier to cover up
with makeup, and can also aid in the healing process. Side
effects are minimal, but may include a temporary whitening of
the skin around the injection point; and occasionally a small
depression forms, which may persist, although often fills
eventually. This method also carries a much smaller risk of
scarring than surgical removal.
Topical retinoids
A group of medications for normalizing the follicle cell
lifecycle are
topical
retinoids such as
tretinoin (brand name Retin-A),
adapalene (brand name Differin), and
tazarotene (brand name Tazorac). Like isotretinoin, they are
related to
vitamin A, but they are administered as topicals and
generally have much milder side effects. They can, however,
cause significant irritation of the skin. The retinoids appear
to influence the cell creation and death lifecycle of cells in
the follicle lining. This helps prevent the
hyperkeratinization of these cells that can create a
blockage.
Retinol, a form of vitamin A, has similar but milder effects
and is used in many over-the-counter moisturizers and other
topical products. Effective topical retinoids have been in use
over 30 years but are available only on prescription so are not
as widely used as the other topical treatments. Topical
retinoids often cause an initial flare up of acne and facial
flushing.
Oral retinoids
Main article:
isotretinoinA daily oral intake of
vitamin A derivative
isotretinoin (marketed as Accutane, Amnesteem, Sotret,
Claravis, Clarus) over a period of 4-6 months can cause
long-term resolution or reduction of acne. It is believed that
isotretinoin works primarily by reducing the secretion of oils
from the glands, however some studies suggest that it affects
other acne-related factors as well. Isotretinoin has been shown
to be very effective in treating severe acne and can either
improve or clear well over 80% of patients. The drug has a much
longer effect than anti-bacterial treatments and will often cure
acne for good. The treatment requires close medical supervision
by a
dermatologist because the drug has many known
side effects (many of which can be severe). About 25% of
patients may relapse after one treatment. In those cases, a
second treatment for another 4-6 months may be indicated to
obtain desired results. It is often recommended that one lets a
few months pass between the two treatments, because the
condition can actually improve somewhat in the time after
stopping the treatment and waiting a few months also gives the
body a chance to recover. Occasionally a third or even a fourth
course is used, but the benefits are often less substantial. The
most common side effects are dry skin and occasional nosebleeds
(secondary to dry nasal mucosa). Oral retinoids also often cause
an initial flare up of acne within a month or so, which can be
severe. There are reports that the drug has damaged the liver of
patients. For this reason, it is recommended that patients have
blood samples taken and examined before and during treatment. In
some cases, treatment is terminated or reduced due to elevated
liver enzymes in the blood, which might be related to liver
damage. Others claim that the reports of permanent damage to the
liver
are unsubstantiated, and routine testing is considered
unnecessary by some dermatologists. Blood triglycerides also
need to be monitored. However, routine testing are part of the
official guidelines for the use of the drug in many countries.
Some press reports suggest that isotretinoin may cause
depression but as of September 2005 there is no agreement in
the medical literature as to the risk. The drug also causes
birth defects if women become pregnant while taking it or take
it while pregnant. For this reason, female patients are required
to use two separate forms of
birth control or vow
abstinence while on the drug. Because of this, the drug is
supposed to be given to females as a last resort after milder
treatments have proven insufficient. Restrictive rules (see
iPledge program) for use were put into force in the USA
beginning in March 2006 to prevent misuse, causing occasioned
widespread editorial comment.[40]
Phototherapy
'Blue' and red light
It has long been known that short term improvement can be
achieved with light. Recently, visible light has been
successfully employed to treat acne (phototherapy)
- in particular intense violet light (405-420 nm) generated by
purpose-built fluorescent lighting,
dichroic bulbs,
LEDs or
lasers. Used twice weekly, this has been shown to reduce the
number of acne lesions by about 64%;[41]
and is even more effective when applied daily. The mechanism
appears to be that a
porphyrin (Coproporphyrin III) produced within P. acnes
generates
free radicals when irradiated by 420 nm and shorter
wavelengths of light.[42]
Particularly when applied over several days, these free radicals
ultimately kill the bacteria.[43]
Since porphyrins are not otherwise present in skin, and no UV
light is employed, it appears to be safe, and has been licensed
by the
U.S.
FDA.[44]
The treatment apparently works even better if used with red
visible light (660 nanometer) resulting in a 76% reduction of
lesions after 3 months of daily treatment for 80% of the
patients;[45]
and overall clearance was similar or better than benzoyl
peroxide. Unlike most of the other treatments few if any
negative side effects are typically experienced, and the
development of bacterial resistance to the treatment seems very
unlikely. After treatment, clearance can be longer lived than is
typical with topical or oral antibiotic treatments; several
months is not uncommon. The equipment or treatment, however, is
relatively new and reasonably expensive to buy initially,
although the total cost of ownership can be similar to many
other treatment methods (such as the total cost of benzoyl
peroxide, moisturizer, washes) over a couple of years of use.
Photodynamic therapy
In addition, basic science and clinical work by
dermatologists Yoram Harth and Alan Shalita and others has
produced evidence that intense blue/violet light (405-425
nanometer) can decrease the number of inflammatory acne lesion
by 60-70% in 4 weeks of therapy, particularly when the P.
acnes is pretreated with
delta-aminolevulinic acid (ALA), which increases the
production of porphyrins. However this photodynamic therapy is
controversial and apparently not published in a peer reviewed
journal. A phase II trial, while it showed improvement occurred,
failed to show improved response compared to the blue/violet
light alone.[46]
Laser treatment
Laser surgery has been in use for some time to reduce the
scars left behind by acne, but research has been done on lasers
for prevention of acne formation itself. The laser is used to
produce one of the following effects:
- to burn away the follicle sac from which the hair grows
- to burn away the sebaceous gland which produces the oil
- to induce formation of
oxygen in the bacteria, killing them
Since lasers and intense pulsed light sources cause thermal
damage to the skin, there are concerns that laser or intense
pulsed light treatments for acne will induce hyperpigmented
macules (spots) or cause long-term dryness of the skin.
In the
United States, the
FDA has approved several companies, such as Candela Corp.,
to use a cosmetic laser for the treatment of acne. However,
efficacy studies have used very small sample sizes (fewer than
100 subjects) for periods of six months or less, and have shown
contradictory results.[47]
Also, laser treatment being relatively new, protocols remain
subject to experimentation and revision,[48]
and treatment can be quite expensive. Also, some Smoothbeam
laser devices had to be recalled due to coolant failure, which
resulted in painful burn injuries to patients.[49]
Less widely used treatments
-
Aloe vera: there are treatments for acne mentioned in
Ayurveda using herbs such as
Aloe vera,
Neem,
Haldi (Turmeric) and
Papaya. There is limited evidence from medical studies
on some of these products,[50]
although others have been proven effective. Products from
Rubia cordifolia,
Curcuma longa (commonly known as Turmeric),
Hemidesmus indicus (known as ananthamoola or anantmula),
and
Azadirachta indica (Neem) have been shown to have
anti-inflammatory effects, but not aloe vera.[51]
-
Azelaic acid (brand names Azelex, Finevin and Skinoren)
is suitable for mild, comedonal acne.[52]
-
Calendula used in suspension is used as an
anti-inflammatory agent[53]
-
Heat: local heating may be used to kill the bacteria in
a developing pimple and so speed healing.
[54]
-
Naproxen or
ibuprofen are used for some moderate acne for their
anti-inflammatory effect.
-
Nicotinamide, (Vitamin B3) used topically in the form of
a gel, has been shown in a 1995 study to be of comparable
efficacy to topical clindamycin topical antibiotic used for
comparison.[55]
Topical nicotinamide is available both on prescription and
over-the-counter. The property of topical nicotinamide's
benefit in treating acne seems to be its anti-inflammatory
nature. It is also purported to result in increased
synthesis of collagen, keratin, involucrin and flaggrin and
may also according to a cosmetic company be useful for
reducing skin hyperpigmentation (acne scars), increased skin
moisture and reducing fine wrinkles.[56]
-
Tea tree oil (melaleuca oil) dissolved in a carrier (5%
strength) has been used with some success, where it is
comparable to benzoyl peroxide but without excessive drying,
kills P. acnes, and has been shown to be an effective
anti-inflammatory in skin infections.
[50][57][58]
-
Rofecoxib was shown to improve premenstrual
acne vulgaris in a placebo
controlled study.[59]
-
Zinc: Orally administered
zinc gluconate has been shown to be effective in the
treatment of inflammatory acne, although less so than
tetracyclines.[60][61]
-
Comedo extraction
-
Pantothenic acid, (Vitamin B5)[citation
needed]
-
Detoxification is a common method used by alternative
medicine practitioners for the treatment of acne, although
there have been no studies to prove its success.
Detoxification is the process of cleansing the body of
toxins commonly caused by the environment, pharmaceutical
drugs, food, and cosmetics.
