Author:
Diane Thiboutot
Professor of Dermatology
Penn State University, Hershey, PA
Last Update on: 28 July 2008
What is acne?
Acne is a skin condition that affects the hair follicles (pores) of the face, chest, and back. Acne can vary in severity. In mild cases of acne, there are a few blackheads (open comedones) or whiteheads (closed comedones) with a few red or inflamed bumps (papules) and red or inflamed bumps with pus on the surface (pustules). In moderate acne, there are more blackheads and whiteheads and increasing numbers of papules and pustules. Severe acne can be associated with tender red cysts and nodules that can often be accompanied by scarring. The whiteheads, blackheads, papules, pustules, cysts, and nodules are called “acne lesions.” [See Figure 1].
Acne can affect almost anyone, but it is often thought to be a condition that just affects teenagers. Although the majority of people with acne (85%) are between the ages of 12 and 18, acne often affects adults and sometimes can affect newborns or infants. During adolescence, acne affects men and women equally but is more prevalent in adult women.
How do acne lesions develop?
Acne starts out underneath the skin where the cells that line the pore become sticky and do not move out of the pore onto the skin surface like normal cells. This results in a microscopic acne lesion called the “microcomedo” that cannot be seen with the naked eye. This microcomedo can turn into any one of the types of acne lesions (whiteheads, blackheads, papules, pustules, cysts). The process of a microcomedo turning into a visible acne lesion can take several weeks. Most acne treatments are designed to prevent microcomedoes from forming and developing into other acne lesions. That is why it is important to apply acne medications to all areas of the skin where acne can develop and not just on the acne lesion itself. Unlike treatments for other conditions, acne treatment can sometimes take several weeks to see improvement, because it is preventing the formation of microcomedoes beneath the skin and their further progression into a visible acne lesion.
What is happening in the skin to cause acne?
Each of 4 factors plays a role in the development of acne, but the exact sequence of events that leads to the development of acne is not known. [1] [Figure 2]
Factor 1. The cells that line the pore don’t readily move out onto the surface of the skin (this is called follicular hyperkeratinization, not follicular plugging, because the pore still has an opening).
Factor 2. The Propionibacterium acnes (P. acnes) bacteria in the skin secrete substances into the pore and the surrounding skin that induce inflammation (redness).
Factor 3. Oil (sebum) production by the oil gland (sebaceous gland) is increased, and it provides a good environment to support the growth of the P. acnes bacteria.
Factor 4. Inflammation: White blood cells that fight off infection are called into the skin near the pore by chemical signals originating from cells or bacteria within the pore. Some studies suggest that the movement of these cells towards the pore may be the first step in starting the acne process. The signal that calls the white blood cells to this area is not yet known. These white blood cells can secrete substances that induce inflammation, in addition to the inflammation induced by the P. acnes bacteria. The very red, sore acne papules or nodules can develop if the lining of the pore ruptures beneath the skin. When this happens, the inflammation and tenderness of the skin greatly intensifies. Sometimes this process happens on its own when the pore becomes enlarged with dead cells, oil, and bacteria. Picking or squeezing at acne can also cause the pore to rupture under the skin, which makes the redness or inflammation worse and can increase the risk of scarring.
What causes my skin to develop acne and what does not?
Many people have various beliefs and perceptions regarding the cause of acne [2]. It is only natural for people to think that their acne results from something they did or didn’t do, something they ate or didn’t eat, or something that they came in contact with, etc. In reality, acne happens for reasons that for the most part are out of our control. We can’t control changes in the cells of our pores, the fact that P. acnes lives on the skin, or the fact that our oil glands produce oil. As young people become teenagers, normal hormones in the body cause the oil glands to grow and secrete more oil on the face, chest, back, and scalp. The P. acnes bacteria live on the skin of teenagers and adults who have acne, and also on the skin of those not affected by acne. Here are some common questions about acne:
1. Do I have acne because I don’t wash my face enough?
No, the changes in the cells of the pores occur too deep in the pore to be affected by vigorous washing or scrubbing. In fact, vigorous washing or scrubbing serves more to aggravate acne than to help it. Gentle face washing to remove surface oils 2 or 3 times a day is recommended to improve the oily appearance of the skin, but face washing will not prevent acne from forming.
2. Do I have acne because I eat fatty foods, sugary foods (including chocolate), drink milk, or eat meat?
Most studies suggest that individual foods do not cause acne. Recently some studies suggest that diets low in refined sugars and sugar-containing foods (a low glycemic index diet) may be better for acne [3]. Some studies suggest that there could be a link between acne and milk, but there is no direct evidence for this. Milk contains calcium that is especially important for bone development in young people. Any diet where milk is eliminated or reduced would need to have alternative sources of calcium. Some people are concerned about hormones in meats and other foods. There have been no studies to link these foods to the development of acne.
3. Will the sun make my acne better?
Some people feel that their acne is better during the summer. This may be due to the fact that oftentimes, teenagers (and adults) may be less stressed during the summer, away from school or on vacation. Many people’s moods improve in sunny environments. These potential benefits can still be achieved while protecting skin health by using a sunscreen or other protective measures.
When will my acne go away?
For reasons that we do not understand, most teenagers affected by acne (boys in particular) notice that their acne starts to go away as they get into their 20s. For some girls, acne can persist or even develop for the first time in their 20s or later. It is thought that in adulthood, hormones influence acne in women more than in men. This may go against what one would think, since men have higher levels of acne-causing hormones, but it seems that women’s skin is more sensitive to hormones when it comes to developing acne. Some researchers think that the peak acne years (ages 12-18) coincide with the peak levels of a different hormone called insulin-like growth factor-1 (IGF-1), that regulates growth [4]. Levels of IGF-1 start to decline as people get into their 20s when the growth spurt stops. Whether the decline in IGF-1 accounts for the decline in acne at this age is not certain.
Will my acne leave scars?
The best way to avoid acne scarring is to avoid picking or squeezing acne lesions and to seek appropriate care for your acne before it leads to scarring. There is a lot of variation in the way that people’s skin reacts to having acne. It may take up to a year before a person can tell what kind of marks or scars could be left by their acne. As soon as an acne lesion heals, many people can have flat marks (level with the skin) that can be red, pink, purple, brown, dark brown, or black. These are called "postinflammatory macules" [Figure 1]. In most cases, if a person hasn’t picked or squeezed at their acne, these darker areas will lighten over time and won’t leave a permanent mark or scar. If someone’s acne is changing the contour of their skin leaving deep marks (beneath the surface contour of the face), this type of acne can heal with permanent scarring. Again, it takes almost up to a year before the skin fully heals. If after this time there are still depressed scars or other marks, these may be permanent.
What can I do about my acne?
Skin health benefits from a healthy lifestyle that includes a balanced diet that contains fruits, vegetables, and whole grains with limited refined sugars in addition to exercise, adequate sleep, and management of stress. Beginning to lead a healthy lifestyle as a teenager can have long-term benefits into adulthood. Proper skin care is geared to the type of skin that you have. In all cases it is important to cleanse the skin gently and avoid unnecessary rubbing or scrubbing of the acne. Using a soft washcloth or just the fingers is best. If the skin is oily, mild soaps or acne washes work well to remove the surface oils. If the skin is dry, gentle cleansing should be followed by use of a moisturizer. It is a good idea to consider a moisturizer that contains a sunscreen. Some people are concerned that moisturizers or other makeup could cause or aggravate acne. In most cases, this is not true. Most products from major companies are now tested in advance to show that they are noncomedogenic (don’t cause acne). Some people have used the strips designed to remove debris from the pores. There is no harm with gentle use of these strips, which some people feel improves the appearance of their skin.
What are the best products to use for my acne?
The best over-the-counter ingredient for acne is benzoyl peroxide. It is the most potent agent available to kill the P. acnes bacteria and should be the first place to start in looking for an over-the-counter acne treatment. Benzoyl peroxide is found in some acne cleansers, acne bar soaps, acne creams and gels, and in some of the popular products advertised on television. Since some products change their ingredients from time to time, the best way to find a benzoyl peroxide–containing product is to read the fine print—the list of ingredients on the back of the container or package. A small percentage of people may be allergic to benzoyl peroxide, as evidenced by excess redness, itching or peeling of the skin following its use. In these cases, benzoyl peroxide should be avoided. Salicylic acid is also a beneficial over-the-counter acne ingredient, and it is found in many products and in makeup designed for people with acne. Again keep in mind, all acne products work best when applied to the entire affected area, not just the acne lesions themselves. Spot treatment alone shortchanges the rest of your face. Keep in mind that benzoyl peroxide can bleach clothing, towels, and sometimes hair, so it is important to properly rinse off benzoyl peroxide washes from the chest and back and not to apply it too close to the hairline.
When should I see a doctor?
If you have used a benzoyl peroxide containing product for 6-8 weeks and there is no improvement in your acne, if your acne is scarring, or if your acne is severely affecting your self-esteem or ability to interact with others, you should see a doctor for acne treatment.
What type of doctor should I see?
Doctors that specialize in the treatment of skin conditions are called dermatologists, but many doctors treat acne including family physicians, pediatricians, internists, and others. In some cases, your primary care physician (family physician, pediatrician, or internist) can treat your acne or refer you to a dermatologist if you need additional treatment. Listings of dermatologists in your area can be found on the web site for the American Academy of Dermatology (www.aad.org).
What should I expect when I see a doctor for my acne?
Most doctors will want to know when your acne started, what you are currently using for your acne, what you have used in the past, and how you feel about having acne. For women, your doctor will also want to know if your menstrual periods are regular and if your acne flares with your menstrual periods. Doctors will visually examine your face, chest, and back to determine the extent of your acne, what types of acne lesions you have, and if you have signs of acne scarring. Doctors will usually then make recommendations for your skin care, give prescriptions to help clear the acne and in some cases discuss office treatments for your acne.
What types of prescription medications are used for acne? [5,6]
Prescription acne medications can be divided into topical treatments (such as washes, creams, lotions, gels) and oral treatments (such as antibiotic pills). More often that not, you may receive more than one prescription for your acne. This is because the different acne medications target one or more of the 4 factors that cause acne discussed above. Topical (applied to the skin) treatments include benzoyl peroxide washes, creams, gels, and lotions; topical antibiotics such as clindamycin or erythromycin; combination products containing both benzoyl peroxide and a topical antibiotic such as clindamycin (Duac, Benzaclin); topical retinoids such as tretinoin (Retin A and others), adapalene (Differin), and tazarotene (Tazorac); or combinations of tretinoin and clindamycin (Ziana). Benzoyl peroxide and topical antibiotics can kill the P. acnes bacteria. Topical retinoids can reverse the changes in the cells lining the pores and prevent the formation of the microcomedo. They can also reduce inflammation in acne. The combination products target multiple factors that cause acne.
Oral (taken by mouth) medications for acne include antibiotics such as tetracycline, doxycycline, or minocycline; hormonal therapies such as oral contraceptives; and isotretinoin (Accutane and others). Oral antibiotics work to kill the P. acnes bacteria and reduce inflammation. Oral contraceptives can be used to reduce the effects of hormones on acne in women. Isotretinoin is the most potent drug for acne that affects all 4 factors that cause this condition. It is generally taken for about 20 weeks. Isotretinoin can have serious side effects (see below) and its use requires close monitoring.
What should I expect from my acne treatment and how fast does it work?
Your doctor should discuss with you what to expect from your treatment in terms of possible side effects, the time it takes for the medication to work, how it should be applied or taken and how often, etc. The most common side effects from topical acne treatment are redness, dryness, scaling, or peeling of the skin. In most cases, these effects resolve after a couple of weeks. Regular use of a moisturizer helps to reduce these potential side effects. The most common side effects of oral antibiotics used for acne are allergic reactions (hives, rashes, swelling), stomach upset, potential sun sensitivity, or headache with some antibiotics. If there is concern about an allergic reaction, the medication should be stopped and you should contact your doctor. Hormonal therapies can be associated with an increased risk of blot clots in some patients. Isotretinoin can cause birth defects if a woman becomes pregnant on therapy or within a month afterwards. There are strict guidelines in place regarding preventing pregnancy in women receiving isotretinoin. Reports of depression and suicide have occurred in patients treated with isotretinoin. As mentioned above, the use of isotretinoin requires close monitoring.
In general, it takes at least 6-8 weeks to notice the full effect of an acne treatment regimen, so it is best to continue to use the medication as prescribed until you see your doctor again for a follow-up evaluation of your acne and your progress. It is also best to apply topical medications to the whole affected area whether it is the face, chest, or back. As mentioned before, by applying the medication this way, you’ll be helping to prevent the development of acne, rather than chasing after acne that has already had the chance to develop if you use spot treatment alone. When using topical acne treatment, more is not always better; you should use it as directed by your doctor, usually only a small amount. Application of medication to the back is often difficult. Help from someone else can be beneficial or use of a sponge with a handle to apply the medication to difficult to reach areas.
What types of office procedures are there for acne? [7]
There may be tremendous appeal in the prospect that acne can be kept under control with laser or light treatments or a chemical peels that could replace the need for taking pills, using washes, or applying topical medications. Unfortunately medical science is not quite there yet. Laser and light treatments for acne are approved by the US Food and Drug Administration (FDA). However, these are approved as devices (as opposed to drugs), and the criteria for approval differ between drugs and devices. Approval of a device requires less information about how effective the device is in treating acne compared with the amount of information required for drugs. As time goes on, laser and light therapies will continue to improve and more studies to compare them to standard acne medications will be conducted. In most cases, insurance does not cover laser and light treatments for acne, which can sometimes be expensive.
How long will I need treatment for my acne?
There is no one answer to this question, apart from “as long as the acne is active and bothersome.” The length of treatment for acne varies depending upon your family history of acne, the age at which you developed significant acne, your current age, and how your skin responds to treatment. Most acne occurs between the ages of 12 and 18. If someone has a family history of severe acne, it is possible that they could also develop severe acne that may require treatment as long as the acne is active possibly for several years. If someone has significant acne at an early age, they may require treatment throughout their teenage years. Adults with acne, women in particular, may need treatment for as long as their acne is active, which could be several years.
What can be done about my acne scarring? [8]
The best thing is to see a doctor to get the acne under control to prevent additional scarring. Although many treatments are available for acne scarring, there is no guarantee that the skin will be perfect after treatment for acne scars. Treatments for scarring can be performed by some dermatologists, plastic surgeons, and other physicians. Types of procedures include laser treatments, small skin grafts, release of scars from underlying skin, and chemical peels. Dermabrasion is no longer the standard treatment for acne scarring. It is best to get a consultation with a doctor to learn about the best treatments for your type of scarring and to get an estimate of the costs involved.
Is there new research on acne?
As medical science makes advances in understanding the factors that control inflammation, infection, and lipid metabolism in the body and in skin diseases, there are more opportunities to unravel the exact sequence of events leading to the development of acne. Research on acne and skin disease is supported by the US government (The National Institutes of Health, National Institute of Arthritis, Musculoskeletal and Skin Diseases www.niams.nih.gov), the Dermatology Foundation (www.dermatologyfoundation.org), the American Acne and Rosacea Society (www.acnesociety.org), international organizations, and many pharmaceutical and cosmetic companies.
Where can I get more information about acne?
Additional information about acne can be found at each of these websites:
The American Academy of Dermatology www.aad.org
National Institute of Arthritis, Musculoskeletal and Skin Diseases
•(English) www.niams.nih.gov/Health_info/acne
•(Spanish) www.niams.nih.gov/Portal_en_espanol/informacion_de_salud/acne
Medline Plus (National Library of Medicine) www.nlm.nih.gov/medlineplus/acne.html
References
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Pharmacologic modulation of sebaceous gland activity: mechanisms and clinical applications. Dermatologic Clinics. 25(2):137-46, 2007
2. Tan JK. Vasey K. Fung KY. Beliefs and perceptions of patients with acne.
J Am Acad Dermatol 44(3):439-45, 2001
3. Smith RN. Mann NJ. Braue A. Makelainen H. Varigos GA.
The effect of a high-protein, low glycemic-load diet versus a conventional, high glycemic-load diet on biochemical parameters associated with acne vulgaris: a randomized, investigator-masked, controlled trial. J Am Acad Dermatol 57(2):247-56, 2007
4. Rosenfield RL, Deplewski D. Role of androgens in the developmental biology of the pilosebaceous unit. Am J Medicine 98(1A):80S-88S, 1995
5. Strauss JS. Krowchuk DP. Leyden JJ. Lucky AW. Shalita AR. Siegfried EC. Thiboutot DM. Van Voorhees AS. Beutner KA. Sieck CK. Bhushan R. American Academy of Dermatology/American Academy of Dermatology Association. Guidelines of care for acne vulgaris management. J Am Acad Dermatol 56(4):651-63, 2007
6. Gollnick H. Cunliffe W. Berson D. Dreno B. Finlay A. Leyden JJ. Shalita AR. Thiboutot D. Global Alliance to Improve Outcomes in Acne. Management of acne: a report from a Global Alliance to Improve Outcomes in Acne. J Am Acad Dermatol 49(1 Suppl):S1-37, 2003
7. Taub A. Procedural treatments for acne vulgaris. Dermatol Surg 33: 1005-1026, 2007.
8. Goodman GJ and Baron JA. The management of postacne scarring. Dermatol Surg 33: 1175-1188, 2007
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