Acne is caused when tiny holes in the skin, known as hair follicles, become blocked.
Sebaceous glands are tiny glands found near the surface of your skin. The glands are attached to hair follicles, which are small holes in your skin that an individual hair grows out of.
Sebaceous glands lubricate the hair and the skin to stop it drying out. They do this by producing an oily substance called sebum.
In acne, the glands begin to produce too much sebum. The excess sebum mixes with dead skin cells and both substances form a plug in the follicle.
If the plugged follicle is close to the surface of the skin, it bulges outwards, creating a whitehead. Alternatively, the plugged follicle can be open to the skin, creating a blackhead.
Normally harmless bacteria that live on the skin can then contaminate and infect the plugged follicles, causing papules, pustules, nodules or cysts.
Teenage acne is thought to be triggered by increased levels of a hormone called testosterone, which occurs during puberty. The hormone plays an important role in stimulating the growth and development of the penis and testicles in boys, and maintaining muscle and bone strength in girls.
The sebaceous glands are particularly sensitive to hormones. It's thought that increased levels of testosterone cause the glands to produce much more sebum than the skin needs.
Acne can run in families. If your parents had acne, it's likely that you'll also develop it.
One study has found that if both your parents had acne, you're more likely to get more severe acne at an early age. It also found that if one or both of your parents had adult acne, you're more likely to get adult acne too.
More than 80% of cases of adult acne occur in women. It's thought that many cases of adult acne are caused by the changes in hormone levels that many women have at certain times.
Despite being one of the most widespread skin conditions, acne is also one of the most poorly understood. There are many myths and misconceptions about it:
So far, research hasn't found any foods that cause acne. Eating a healthy, balanced diet is recommended because it's good for your heart and your health in general.
Most of the biological reactions that trigger acne occur beneath the skin, not on the surface, so the cleanliness of your skin has no effect on your acne. Washing your face more than twice a day could just aggravate your skin.
This could actually make symptoms worse and may leave you with scarring.
Having sex or masturbating won't make acne any better or worse.
There's no conclusive evidence that prolonged exposure to sunlight or using sunbeds or sunlamps can improve acne. Many medications used to treat acne can make your skin more sensitive to light, so exposure could cause painful damage to your skin, and also increase your risk of skin cancer.
You can't pass acne on to other people.
Treatment for acne depends on how severe it is. It can take several months of treatment before acne symptoms improve.
The various treatments for acne are outlined below.
If you just have a few blackheads, whiteheads and spots, you should be able to treat them successfully with over-the-counter gels or creams (topical treatments) that contain benzoyl peroxide.
Treatments from your GP
See your GP if your acne is more widespread, as you probably need prescription medication. For example, if:
- you have a large number of papules and pustules
- over-the-counter medication hasn't worked
Prescription medications that can be used to treat acne include:
- topical retinoids
- topical antibiotics
- azelaic acid
- antibiotic tablets
- in women, the combined oral contraceptive pill
- isotretinoin tablets
If you have severe acne, your GP can refer you to an expert in treating skin conditions (dermatologist). For example, if you have:
- a large number of papules and pustules on your chest and back, as well as your face
- painful nodules
A combination of antibiotic tablets and topical treatments is usually the first treatment option for severe acne. If this doesn't work, a medication called isotretinoin may be prescribed.
Hormonal therapies or the combined oral contraceptive pill can also be effective in women who have acne. However, the progestogen-only pill or contraceptive implant can sometimes make acne worse.
Many of these treatments can take 2 to 3 months before they start to work. It's important to be patient and persist with a recommended treatment, even if there's no immediate effect.
Topical treatments (gels, creams and lotions)
Benzoyl peroxide
Benzoyl peroxide works as an antiseptic to reduce the number of bacteria on the surface of the skin. It also helps to reduce the number of whiteheads and blackheads, and has an anti-inflammatory effect.
Benzoyl peroxide is usually available as a cream or gel. It's used either once or twice a day. It should be applied 20 minutes after washing to all of the parts of your face affected by acne.
It should be used sparingly, as too much can irritate your skin. It also makes your face more sensitive to sunlight, so avoid too much sun and ultraviolet (UV) light, or wear sun cream.
Benzoyl peroxide can have a bleaching effect, so avoid getting it on your hair or clothes.
Common side effects of benzoyl peroxide include:
- dry and tense skin
- a burning, itching or stinging sensation
- some redness and peeling of the skin
Side effects are usually mild and should pass once the treatment has finished.
Most people need a 6 week course of treatment to clear most or all of their acne. You may be advised to continue treatment less frequently to prevent acne returning.
Topical retinoids
Topical retinoids work by removing dead skin cells from the surface of the skin (exfoliating) which helps to prevent them building up within hair follicles.
Tretinoin and adapalene are topical retinoids used to treat acne. They're available in a gel or cream and are usually applied once a day before you go to bed.
Apply to all the parts of your face affected by acne 20 minutes after washing your face.
It's important to apply topical retinoids sparingly and avoid excessive exposure to sunlight and UV.
Topical retinoids aren't suitable for use during pregnancy, as there's a risk they might cause birth defects.
The most common side effects of topical retinoids are mild irritation and stinging of the skin.
A 6 week course is usually required, but you may be advised to continue using the medication less frequently after this.
Topical antibiotics
Topical antibiotics help kill the bacteria on the skin that can infect plugged hair follicles. They're available as a lotion or gel that is applied once or twice a day.
A 6 to 8 week course is usually recommended. After this, treatment is usually stopped, as there's a risk that the bacteria on your face could become resistant to the antibiotics. This could make your acne worse and cause additional infections.
Side effects are uncommon, but can include:
- minor irritation of the skin
- redness and burning of the skin
- peeling of the skin
Azelaic acid
Azelaic acid is often used as an alternative treatment for acne if the side effects of benzoyl peroxide or topical retinoids are particularly irritating or painful.
Azelaic acid works by getting rid of dead skin and killing bacteria. It's available as a cream or gel and is usually applied twice a day (or once a day if your skin is particularly sensitive).
The medication doesn't make your skin sensitive to sunlight, so you don't have to avoid exposure to the sun.
You'll usually need to use azelaic acid for a month before your acne improves.
The side effects of azelaic acid are usually mild and include:
- burning or stinging skin
- itchiness
- dry skin
- redness of the skin
Antibiotic tablets
Antibiotic tablets (oral antibiotics) are usually used in combination with a topical treatment to treat more severe acne.
In most cases, a class of antibiotics called tetracyclines is prescribed, unless you're pregnant or breastfeeding.
Pregnant or breastfeeding women are usually advised to take an antibiotic called erythromycin, which is known to be safer to use.
It usually takes about 6 weeks before you notice an improvement in your acne.
Depending on how well you react to the treatment, a course of oral antibiotics can last 4 to 6 months.
Tetracyclines can make your skin sensitive to sunlight and UV light, and can also make the oral contraceptive pill less effective during the first few weeks of treatment.
You'll need to use an alternative method of contraception, such as condoms, during this time.
Hormonal therapies
Hormonal therapies can often benefit women with acne, especially if the acne flares up around periods or is associated with hormonal conditions such as polycystic ovary syndrome.
If you don't already use it, your GP may recommend the combined oral contraceptive pill, even if you're not sexually active. This combined pill can often help improve acne in women, but may take up to a year before the full benefits are seen.
Co-cyprindiol
Co-cyprindiol is a hormonal treatment that can be used for more severe acne that doesn't respond to antibiotics. It helps to reduce the production of sebum.
You'll probably have to use co-cyprindiol for 2 to 6 months before you notice a significant improvement in your acne.
There's a small risk that women taking co-cyprindiol may develop breast cancerin later life.
For example, out of a group of 10,000 women who haven't taken co-cyprindiol, you would expect 16 of them to develop breast cancer by the time they were 35. This figure rises to 17 or 18 for women who were treated with co-cyprindiol for at least 5 years in their early twenties.
There's also a very small chance of co-cyprindiol causing a blood clot. The risk is estimated to be around 1 in 2,500 in any given year.
It's not thought to be safe to take co-cyprindiol if you're pregnant or breastfeeding. Women may need to have a pregnancy test before treatment can begin.
Other side effects of co-cyprindiol include:
- bleeding and spotting between your periods, which can sometimes occur for the first few months
- headaches
- sore breasts
- mood changes
- loss of interest in sex
- weight gain or weight loss
Isotretinoin
Isotretinoin has a number of beneficial effects:
- it helps to normalise sebum and reduce how much is produced
- it helps to prevent follicles becoming clogged
- it decreases the amount of bacteria on the skin
- it reduces redness and swelling in and around spots
However, the drug can also cause a wide range of side effects. It's only recommended for severe cases of acne that haven't responded to other treatments.
Because of the risk of side effects, isotretinoin can only be prescribed by a specially trained GP or a dermatologist.
Isotretinoin is taken as a tablet. Most people take a 4 to 6 month course. Your acne may get worse during the first 7 to 10 days of treatment. However, this is normal and soon settles.
Common side effects of isotretinoin include:
- inflammation, dryness and cracking of the skin, lips and nostrils
- changes in your blood sugar levels
- inflammation of your eyelids (blepharitis)
- inflammation and irritation of your eyes (conjunctivitis)
- blood in your urine
Rarer side effects of isotretinoin include:
- inflammation of the liver (hepatitis)
- inflammation of the pancreas (pancreatitis)
- kidney disease
Because of the risk of these rarer side effects, you'll need a blood test before and during treatment.
Isotretinoin and birth defects
Isotretinoin will damage an unborn baby. If you're a woman of childbearing age:
- don't use isotretinoin if you're pregnant or you think you're pregnant
- use 1, or ideally 2, methods of contraception for 1 month before treatment begins, during treatment and for 1 month after treatment has finished
- have a pregnancy test before, during and after treatment
You'll be asked to sign a form confirming that you understand the risk of birth defects and are willing to use contraceptives to prevent this risk, even if you're not currently sexually active.
If you think you may have become pregnant when taking isotretinoin, contact your dermatologist immediately.
Isotretinoin is also not suitable if you're breastfeeding.
Isotretinoin and mood changes
There have been reports of people experiencing mood changes while taking isotretinoin. There's no evidence that these mood changes were the result of the medication.
However, as a precaution, contact your doctor immediately if you feel depressed or anxious, have feelings of aggression or suicidal thoughts.
Non-pharmaceutical treatments
Several treatments for acne don't involve medication.
These include:
- comedone extractor – a small pen-shaped instrument that can be used to clean out blackheads and whiteheads
- chemical peels – where a chemical solution is applied to the face, causing the skin to peel off and new skin to replace it
- photodynamic therapy – where light is applied to the skin in an attempt to improve symptoms of acne
However, these treatments may not work and can't be routinely recommended.
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