Anti-Acne Products PDF

Anti-Acne Products Dr. Maha N Abu Hajleh 1  Introduction ❑ Acne vulgaris It is a common dermatological disorder of the pilosebaceous unit that has a complex pathophysiology and can be triggered by a number of factors. It primarily affects te...

Anti-Acne Products Dr. Maha N Abu Hajleh 1  Introduction ❑ Acne vulgaris It is a common dermatological disorder of the pilosebaceous unit that has a complex pathophysiology and can be triggered by a number of factors. It primarily affects teenagers; however, it can also affect adults. Acne is estimated to affect 40–50 million people in the US, with an 85% prevalence in those aged 12–24 years, which makes it the most common skin disorder that dermatologists treat. With regard to gender, acne is significantly higher among women than among men in all age groups Dr. Maha Abu Hajleh-AAU 2 Major factors contributing to the development of acne vulgaris Dr. Maha Abu Hajleh-AAU 3  The major factors include the following ▪ Increased sebum production by the pilosebaceous unit. ◾ Increased androgen activity. ◾ Abnormally increased keratinocyte production and desquamation with subsequent plugging of the follicles. ◾ Microbial colonization of the pilosebaceous unit by a commensal bacterial Propionibacterium acnes (P. acnes). ◾ Inflammation and immune reactions. Dr. Maha Abu Hajleh-AAU 4 Dr. Maha Abu Hajleh-AAU 5  Development of Acne Acne occurs when the hair follicles become plugged with sebum and dead skin cells. The pathogenesis of acne is still not clearly understood, and the development process can be summarized as follows: For reasons not clearly understood, the body produces more epidermal cells (the process is referred to as “hyperkeratinization”) and excess sebum. Dr. Maha Abu Hajleh-AAU 6 Dr. Maha Abu Hajleh-AAU 7 Dr. Maha Abu Hajleh-AAU 8 Dr. Maha Abu Hajleh-AAU 9  Development of Acne Unlike the normal case where cells that are shed within the follicle are swept out of the follicle onto the surface of the skin along with the secreted sebum, in acne, the excess amount of sebum and cells released into the follicle cannot get out to the skin surface, but they build up in the hair follicles. At the same time, the draining duct widens and the sebaceous gland grows larger and wider due to the accumulated material. Dr. Maha Abu Hajleh-AAU 10  Development of Acne ▪ They form a plug, and it creates a sebum-rich, oxygen-poor environment, which is ideal for the proliferation of Propionibacterium acnes (P. acnes). ▪ These bacteria produce enzymes that hydrolyze the triglycerides in the sebum, and this leads to further hyperkeratinization and inflammation. ▪ This early stage of acne is called a microcomedo. ▪ Microcomedones occur under the skin and are small enough that the human eye cannot see them. Dr. Maha Abu Hajleh-AAU 11  Causes of Acne Microcomedones require special attention because they represent the primary precursor lesions that will evolve into either non inflammatory or inflammatory lesions. The exact underlying cause of acne and follicular blockage is not known. Dr. Maha Abu Hajleh-AAU 12  Causes of Acne 1-Hormones: Androgens are usually referred to as male hormones, which can also be found in women’s blood, but in a smaller amount. Their level increases in boys and girls during puberty and causes the sebaceous glands to enlarge and produce more sebum. It is believed that androgens play a crucial role in the development of acne. Hormonal changes related to pregnancy, and the use of contraceptives can also affect sebum production. Additionally, numerous other hormones, including growth hormone, and insulin-like growth factor have been identified as potential causative factors for the development of acne. Dr. Maha Abu Hajleh-AAU 13  Causes of Acne 2- Propionibacterium acnes P. acnes is an anaerobic bacteria present in acne lesions. The significance of the involvement of P. acnes in acne pathogenesis is still controversial.. It can promote inflammation through a variety of mechanisms. P. acnes stimulates inflammation by producing pro-inflammatory mediators that diffuse through the follicle wall. Dr. Maha Abu Hajleh-AAU 14  Causes of Acne 3-Diet: The influence of diet on the induction and aggravation of acne has been a matter of intense debate over the past few years. Major dietary factors include dairy products, mainly milk, foods with glycemic load, such as bread, bagels, and spaghetti. This evidence, to date, does not demonstrate that diet causes acne, but can aggravate or promote it. Dr. Maha Abu Hajleh-AAU 15  Causes of Acne 3-Diet: The influence of diet on the induction and aggravation of acne has been a matter of intense debate over the past few years. Major dietary factors include dairy products, mainly milk, foods with glycemic load, such as bread, bagels, and spaghetti. This evidence, to date, does not demonstrate that diet causes acne, but can aggravate or promote it. Dr. Maha Abu Hajleh-AAU 16  Causes of Acne 4-Other factors may include ▪ Sunlight ▪ It is not clear whether UV radiation or visible light worsens, improves, or has no effect on acne. Some studies suggest that sunlight has a positive effect on acne, while other studies did not demonstrate any significant effects. ▪ Light therapy is increasingly used in acne treatment, and some studies have shown evidence of sunlight being beneficial to acne patients. ▪ Photosensitivity is an issue with commonly used, efficacious medical treatments of acne, including tetracyclines and isotretinoin. Dr. Maha Abu Hajleh-AAU 17  Causes of Acne Dr. Maha Abu Hajleh-AAU 4-Other factors may include ▪ Facial Hygiene and Face Cleansing: ✓ A common perception is that poor levels of hygiene lead to the development or exacerbation of acne. ✓ Aggressive cleansing, however, can lead to disruption of the skin barrier, increased TEWL, rough and irritable skin, increased bacterial colonization, increased comedonal formation, burning, and stinging. ✓ Acne cleansers should have a pH similar to that of the skin. Facials scrubs containing abrasive particles can also traumatize the skin and can exacerbate the symptoms and, therefore, are often recommended by dermatologists not to be used for acne patients. Products containing dyes and perfumes should be avoided for acne patients since they may exacerbate acne and irritate the skin. 18  Causes of Acne 4-Other factors may include ▪ Makeup Use ✓ (Facial foundations and concealers) trigger and/or worsen acne. Therefore, they were recommended to be avoided by dermatologists. ✓ However, it has been shown in new studies that acne patients can benefit from the use of color cosmetic products even using those without any active ingredients since these products can cover up blemishes, redness, and even scars and can significantly improve patients’ self-image. Dr. Maha Abu Hajleh-AAU 19  Causes of Acne 4-Other factors may include ◾ Additional Factors ✓ In addition to the factors listed earlier, stress, genetic factors, and certain medications, including corticosteroids. The role of smoking in triggering acne is still controversial. Dr. Maha Abu Hajleh-AAU 20  Symptoms and Types of Acne Vulgaris The clinical presentation of acne can range from mild comedonal (i.e., non-inflammatory) form to severe inflammatory cystic acne. It primarily affects the areas of skin with the densest population of sebaceous follicles; these areas include the face, the upper part of the chest, and the back. Dr. Maha Abu Hajleh-AAU 21  Symptoms and Types of Acne Vulgaris ▪ Non-inflammatory lesions: They consist of open and closed comedones, which are neither inflamed nor red because the follicle walls are intact. Unlike microcomedones, these lesions are large enough to be seen by the naked eye. 22 Dr. Maha Abu Hajleh-AAU  Symptoms and Types of Acne Vulgaris Non-inflammatory lesions: ❖ Blackheads (Open Comedones): They are follicles that have a wider opening filled with sebum and dead cells. They are called blackheads due to the dark appearance of the plugs in the follicles. The dark color is caused by the exposure of the top of the comedo to oxygen. Open comedones rarely develop into inflammatory lesions. Dr. Maha Abu Hajleh-AAU 23 Dr. Maha Abu Hajleh-AAU 24  Symptoms and Types of Acne Vulgaris Non-inflammatory lesions: ❖ Whiteheads (Closed Comedones): Occur when the follicle’s opening remains closed. They are more difficult to see; they usually have normal skin color. A closed comedo is not an inflammatory lesion; however, it is much more likely to progress into an inflammatory lesion than an open comedo. Dr. Maha Abu Hajleh-AAU 25 Dr. Maha Abu Hajleh-AAU 26  Symptoms and Types of Acne Vulgaris ❖ Inflammatory acne lesions They are characterized by the presence of papules, pustules, nodules, and cysts. These lesions are red and inflamed due to blood penetrating the follicle after the follicle has ruptured. The closed comedo becomes larger and more packed due to debris and inflammation from P. acnes. P. acnes produces enzymes that make the follicle wall weaker, and eventually it ruptures. At this point, white blood cells along with red blood cells migrate to the place of rupture to fight against P. acnes and contain the rupture. This is when the lesion turns red. At this point, the closed comedo turns into a papule. Dr. Maha Abu Hajleh-AAU 27  28 Dr. Maha Abu Hajleh-AAU  Symptoms and Types of Acne Vulgaris Inflammatory acne lesions Papules are small, raised, usually red, and tender bumps under the skin. These are the primary inflammatory lesions. Pustules are red, tender bumps with white pus at their tips. While fighting the infection, white blood cells die and create pus. As the pus reaches the skin surface, a pustule is formed, also called a pimple. Dr. Maha Abu Hajleh-AAU 29  Symptoms and Types of Acne Vulgaris Inflammatory acne lesions Nodules are deep lesions, similar to papules, but much deeper in the dermis. Nodules often occur when rupture of the follicle wall happens deep down at the bottom of the wall. Nodules are hard to touch, more painful than other lesion types, and deep red or purple in color. Nodules may even involve more than one follicle, forming a large pocket of infection. Dr. Maha Abu Hajleh-AAU 30  Symptoms and Types of Acne Vulgaris Inflammatory acne lesions Cysts are large pus-filled lesion that is the result of a severe inflammatory reaction. As they affect deeper layers of the skin, cystic acne frequently causes scarring. Dr. Maha Abu Hajleh-AAU 31  Classification of Acne Vulgaris ❖ Acne vulgaris ▪ It is also often graded based on its severity, including the number of comedones, inflammatory lesions, total lesion count, and cysts. ▪ Acne is categorized broadly into mild, moderate, and severe forms. This classification is important as it is used as a basis for selecting the treatment. Dr. Maha Abu Hajleh-AAU 32  Classification of Acne Vulgaris ❖ Acne vulgaris Mild acne is typically limited to the face and is characterized by the presence of non inflammatory closed and open comedones with few inflammatory lesions. Moderate acne is characterized by an increased number of inflammatory papules and pustules on the face and also often affects other body parts. Severe acne is characterized by nodules and cysts. In these cases, facial lesions are often accompanied by widespread disease of other body parts, including the neck, chest, and back. Dr. Maha Abu Hajleh-AAU 33 Dr. Maha Abu Hajleh-AAU 34  Treatment of Acne Vulgaris Careful assessment of the morphology and severity of acne is an important first step in management since lesion morphology largely dictates the optimal treatment approach. Today, there are many effective acne treatments. However, it does not mean that every acne treatment works for everyone who has acne. Treatment should be designed to target precursor lesions (microcomedones) and active inflammatory lesions. Dr. Maha Abu Hajleh-AAU 35  Treatment of Acne Vulgaris ▪ Milder cases are best managed with OTC and prescription-only topical regimens. Whereas systemic, prescription-only drugs are indicated in more severe cases. The management of acne can be complex, often requiring aggressive combination therapy and a long-term therapeutic strategy. With most treatments, one may see the first signs of improvement in 4–8 weeks, and the skin may often get worse before it gets better due to the side effects of commonly used medications. Maintenance therapy is usually necessary for many acne patients, as acne lesions have been shown to return after discontinuing a successful treatment regimen. 36 Dr. Maha Abu Hajleh-AAU Topical Treatment Options Topical therapies generally employ OTC actives, such as benzoyl peroxide and salicylic acid, as well as prescription-only antibiotics and retinoids. OTC active ingredients can be found in the relevant part of the OTC monograph, which lists ingredients that are generally recognized as safe and effective for the treatment of acne. These include the following ingredients: Dr. Maha Abu Hajleh-AAU 37  Treatment of Acne Vulgaris Topical Treatment Options Benzoyl Peroxide (BPO) It is a non-antibiotic antimicrobial agent that can kill bacteria by producing reactive oxygen species within the clogged pore. It increases cell turnover, cleans pores, desquamates the skin, and also has anti- inflammatory properties. BPO is available as topical OTC products in a concentration of 2.5–10% in various forms, including Leave-on products (creams, gels, and lotions) Rinse-off products (facial wash). Dr. Maha Abu Hajleh-AAU 38  Treatment of Acne Vulgaris Topical Treatment Options Benzoyl Peroxide (BPO) ❑ It is a mainstay treatment of mild-to-moderate acne, often combined with antibiotics and/or retinoids. Its main side effects include peeling, dryness, burning, and redness of the skin. Irritation typically resolves with continued use during the first month of treatment. Patients should also be warned that BPO may bleach clothing, bedding, and hair. Dr. Maha Abu Hajleh-AAU 39  Treatment of Acne Vulgaris Topical Treatment Options Salicylic Acid (SA): SA has desquamating and comedolytic properties. It is available as OTC products in concentrations of 0.5–2% in various product forms, including ▪ Leave-on products ( lotions, creams, and foams). ▪ Cleansing products (facial wash gels, toners, and cleansing pads). ▪ Several OTC drug–cosmetic combination products containing SA, including foundations and concealers, available on the market. Dr. Maha Abu Hajleh-AAU 40  Treatment of Acne Vulgaris Topical Treatment Options Salicylic Acid (SA): Temporary typical side effects of the topical SA treatment include skin dryness, redness, scaling, itching, and burning. They typically dissipate in a few weeks. Studies indicate that it is less potent than topical retinoids, however, but better tolerated by patients. Therefore, it is an option for patients who cannot tolerate a topical retinoid due to skin irritation. Dr. Maha Abu Hajleh-AAU 41  Treatment of Acne Vulgaris Topical Treatment Options Resorcinol and sulfur They have also been used in the therapy for a long time. However, they are not considered a first-line therapy for acne. These active ingredients are generally available as creams, masks, ointments, and soap bars. Dr. Maha Abu Hajleh-AAU 42  Treatment of Acne Vulgaris Topical Treatment Options (prescription-only drugs ) include the following Topical Retinoids: They are vitamin A derivatives that : Normalize the abnormal desquamation pattern in sebaceous follicles. Decrease the coherence of follicular keratinocytes. Prevent the formation of new microcomedones. Some retinoids also have anti-inflammatory properties. Dr. Maha Abu Hajleh-AAU 43  Treatment of Acne Vulgaris Topical Treatment Options (prescription-only drugs) Topical Retinoids: Currently available FDA-approved topical retinoids include tretinoin, adapalene, and tazarotene; all are available for prescription-only drugs in the US. These ingredients are available in cream, gel, liquid, and microsphere formulations, each at multiple concentrations. Dr. Maha Abu Hajleh-AAU 44  Treatment of Acne Vulgaris Topical Treatment Options (prescription-only drugs ) Topical Retinoids: Topical retinoids are effective ingredients and, therefore, are often recommended for all cases of acne, except when oral retinoids are used. Mild noninflammatory comedonal acne may be treated with retinoid monotherapy. When inflammatory lesions are present, retinoids are combined with antimicrobial therapy or BPO. As retinoids prevent the development of microcomedones, they can also be used for maintenance therapy. Improvement of acne symptoms usually occurs within weeks, and the maximum benefit can be typically expected after 3–4 months of treatment. Dr. Maha Abu Hajleh-AAU 45  Treatment of Acne Vulgaris Topical Treatment Options (prescription-only drugs ) Topical Retinoids: The use of retinoids is limited by their side effects, including transient skin irritation, burning sensation, redness, itching, and peeling. These negative effects can be prevented by selecting lower concentration of active ingredients or modifying the vehicle of the active (e.g., formulating a cream or foam instead of a gel). Dr. Maha Abu Hajleh-AAU 46  47 Dr. Maha Abu Hajleh-AAU  Treatment of Acne Vulgaris Topical Treatment Options (prescription-only drugs) Topical Antibiotics: The commonly used antibiotics for acne include clindamycin and erythromycin. Antibiotics have bacteriostatic and anti-inflammatory properties. They are used for mild-to-moderate acne when inflammatory lesions are present. They are available as gels, creams, lotions, foams, toners, and pads. Dr. Maha Abu Hajleh-AAU 48  Treatment of Acne Vulgaris Topical Treatment Options (prescription-only drugs) Topical Antibiotics: An emerging issue with regard to antibiotic use is antibiotic resistance, which can decrease the antibiotic effectiveness over time. Therefore, antibiotic monotherapy and maintenance therapy alone are not recommended, nor the combination of topical and systemic antibiotics. Current guidelines recommend combining antibiotics with retinoids and/or BPO. BPO can minimize bacterial resistance, while retinoids can provide synergistic comedolytic and antiinflammatory properties. Dr. Maha Abu Hajleh-AAU 49  Treatment of Acne Vulgaris Topical Treatment Options (prescription-only drugs) ❑ Azelaic acid. It is an alternative to retinoids that has comedolytic, antimicrobial, and anti-inflammatory properties. It is, however, not approved by the FDA in the US. Dr. Maha Abu Hajleh-AAU 50  Treatment of Acne Vulgaris Systemic Treatment Options Systemic agents are typically recommended for patients with moderate-to-severe acne. These therapies are also useful in patients with larger surfaces affected, including the neck, chest, and back. In their case, topical treatment would be difficult. Systemic agents include antibiotics, hormones, and an oral retinoid, isotretinoin. Dr. Maha Abu Hajleh-AAU 51  Treatment of Acne Vulgaris Systemic Treatment Options Oral Antibiotics: Most commonly, doxycycline, minocycline, tetracycline, and erythromycin are used. Similar to topical antibiotics, systemic agents have antimicrobial and anti-inflammatory effects. A major problem affecting antibiotic therapy of acne has been bacterial resistance, which has been increasing. As with topical antibiotics, oral antibiotics should be combined with other agents to minimize the development of bacterial resistance and improve treatment efficacy. ▪ Oral antibiotics should be used with topical retinoids or BPO. Dr. Maha Abu Hajleh-AAU 52  Treatment of Acne Vulgaris Systemic Treatment Options Oral Antibiotics: For this reason, dermatologists usually recommend tapering off these medications (i.e., continuously decreasing their dose) as soon as the symptoms begin to improve or as soon as it becomes clear that the drugs do not help. Antibiotics may cause side effects, such as an upset stomach, dizziness, or skin discoloration. Doxycycline can increase sun sensitivity. Tetracyclines can cause teeth discoloration. Dr. Maha Abu Hajleh-AAU Minocycline can lead to skin hyperpigmentation. 53  Treatment of Acne Vulgaris Systemic Treatment Options Isotretinoin: Isotretinoin is an oral retinoid; it is a powerful medication for the treatment of severe acne and moderate acne that does not respond to other treatments. Isotretinoin targets all major components involved in the development of acne: normalizes follicular desquamation, decreases sebum secretion, inhibits the growth of P. acnes , and exerts anti-inflammatory effects. Due to its broad effects, it is usually used as a monotherapy. The common side effects caused by isotretinoin include dryness of the skin, eyes, mouth, lips, and nose; itching; nosebleeds; muscle aches; sun sensitivity; and poor night vision. Dr. Maha Abu Hajleh-AAU 54  Treatment of Acne Vulgaris Systemic Treatment Options Isotretinoin: The drug may also increase the levels of triglycerides and cholesterol in the blood and may increase liver enzyme levels. In addition, isotretinoin may be associated with an increased risk of depression and suicide. It is a teratogenic agent (i.e., can induce malformations in an embryo or a fetus). Therefore, it cannot be safely taken by pregnant women or women who may become pregnant during the course of treatment or within several weeks of concluding treatment. ▪ Female patients must demonstrate a negative pregnancy test before and use contraception when taking this ingredient. Dr. Maha Abu Hajleh-AAU 55  Treatment of Acne Vulgaris Systemic Treatment Options Hormonal Therapy: Hormonal therapy is a useful adjunct therapy in women with moderate-to-severe acne. Hormonal agents commonly used for the treatment of acne are available in two major forms: ❖ Combination oral contraceptives (i.e., contraceptives containing both an estrogen and a progestin), which suppress ovarian androgen production. In addition to being useful adjuncts, oral contraceptives can also be used as part of the maintenance therapy, usually in combination with topical retinoids. ❖ Androgen receptor blockers, which block the effect of androgens on the sebaceous gland. The available androgen receptor blockers are spironolactone, cyproterone acetate, and flutamide; however, none of these are approved by the FDA for acne treatment. 56 Dr. Maha Abu Hajleh-AAU  Treatment of Acne Vulgaris Systemic Treatment Options Hormonal Therapy: Although hormonal therapy may help reduce and/or prevent outbreaks, it is not effective for existing lesions; therefore, it is used as an adjunct rather than a stand-alone therapy. Common side effects of hormonal therapy include headache, breast tenderness, nausea, and depression. The most serious potential complication is a slightly increased risk of heart disease, high blood pressure, and blood clots. Dr. Maha Abu Hajleh-AAU 57  Treatment of Acne Vulgaris Other Treatment Options Chemical Peels: AHA-based peeling preparations have been used in the treatment of acne (AHAs act by desquamating the SC, which results in a smoother appearance). In addition, glycolic acid has a moderate growth inhibitory and bactericidal effect on P. acnes. In low concentrations (4–10%), HAs are components of nonprescription creams and lotions that are promoted as being effective for skin aging. In high concentrations ( > 20%), they can be used as chemical peels to treat various conditions and diseases, including calluses, acne, and Dr. Maha Abu Hajleh-AAU photoaging. 58  Treatment of Acne Vulgaris Other Treatment Options Herbal and alternative therapies Use of these ingredients in acne is widespread. Commonly used herbal ingredients include aloe vera, fruit-derived acids, and tea tree oil. Although these appear to be well tolerated, very limited data exist regarding the safety and efficacy of such agents Dr. Maha Abu Hajleh-AAU 59  Treatment of Acne Vulgaris Other Treatment Options Comedo Extraction: ▪ There are two ways to release the contents of comedones: squeezing with fingertips and using a comedo extractor. There is limited evidence published that comedo removal for acne treatment is effective. ▪ However, it can greatly improve the patient’s appearance, which may positively impact compliance with the treatment program. Dr. Maha Abu Hajleh-AAU 60  Treatment of Acne Vulgaris Other Treatment Options ❑ Optical therapies ▪ Used to treat acne include broad-spectrum continuous-wave visible light (blue and red), intense pulsed light, pulsed dye lasers, potassium titanyl phosphate lasers, photodynamic therapy (PDT), and pulsed diode laser. ▪ Although optical therapy may improve acne initially. Therefore, optical treatments are not included among first-line treatments. ❑ Dietary restriction has not been demonstrated to be of benefit in the treatment of acne. Dr. Maha Abu Hajleh-AAU 61  GLOSSARY OF TERMS ❑ Acne vulgaris: A common dermatological disorder of the pilosebaceous unit that can be characterized by clogged pores. ❑ Antibiotic resistance: The ability of bacteria or other microbes to resist the effects of an antibiotic. ❑ Antibiotic: A drug used to fight infection caused by microorganisms. Dr. Maha Abu Hajleh-AAU 62  GLOSSARY OF TERMS ❑ Blackhead: Open comedo. It is a noninflamed acne lesion that is black due to oxidation of the sebum and bacteria in the plug. ❑ Botanical extract: Extracts from a plant or herb, often used in antiaging products due to their antioxidant, anti-inflammatory, soothing, emolliating, skin lightening, and skin tightening functions. ❑ Comedo: A widened follicle filled with sebum, bacteria, and dead skin cells. Dr. Maha Abu Hajleh-AAU 63  GLOSSARY OF TERMS ❑ Cyst: A large pus-filled inflammatory acne lesion that is the result of a severe inflammatory reaction. ❑ Hyperkeratinization: An increased production of epidermal cells. ❑ Keratolytic: An ingredient that helps soften and shed the stratum corneum. Dr. Maha Abu Hajleh-AAU 64  GLOSSARY OF TERMS ❑ Microcomedo: The first stage of a comedo, and it is the very beginning of a pore blockage. It cannot be seen with the naked eye. ❑ Nodule: A severely inflamed acne lesion occurring when rupture of the follicle wall happens deep down at the bottom of the wall. Nodules are hard to the touch, more painful than other lesion types, and deep red or purple in color. ❑ P. acnes: Propionibacterium acnes are anaerobic bacteria that are associated with the development of acne. Dr. Maha Abu Hajleh-AAU 65  GLOSSARY OF TERMS ❑ Papule: An inflamed acne lesion resembling a small, tender bump under the skin. ❑ Pustule: An inflamed acne lesion resembling a red, tender bump with white pus at its tip. ❑ Retinoids: A class of substances comprising vitamin A (retinol) and its derivatives.They are used in both antiaging products and antiacne products. ❑ Whitehead: Closed comedo. It is a noninflamed acne lesion that is clogged by the buildup of dead skin cells and sebum. Dr. Maha Abu Hajleh-AAU 66  67 Dr. Maha Abu Hajleh-AAU