Salicylic acid is a topically applied beta-hydroxy acid that stops bacteria from reproducing and has keratolytic properties. It opens obstructed skin pores and promotes shedding of epithelial skin cells. Salicylic acid is known to be less effective than retinoid therapy. Dry skin is the most commonly seen side effect with topical application, though darkening of the skin has been observed in individuals with darker skin types.

Azelaic acid has been shown to be effective for mild to moderate acne when applied topically at a 20% concentration. Treatment twice daily for six months is necessary, and is as effective as topical benzoyl peroxide 5%, isotretinoin 0.05%, and erythromycin 2%. Azelaic acid is thought to be an effective acne treatment due to its ability to reduce skin cell accumulation in the follicle, and its antibacterial and anti-inflammatory properties. It has a slight skin-lightening effect due to its ability to inhibit melanin synthesis, and is therefore useful in treating of individuals with acne who are also affected by postinflammatory hyperpigmentation. Azelaic acid may cause skin irritation but is otherwise very safe. It is less effective and more expensive than retinoids.

Using non-oily cleansers and mild soap may not cause as much irritation to the skin as regular soap. Blackheads can be removed across an area with commercially available pore-cleansing strips or the more aggressive cyanoacrylate method used by dermatologists.

Squeezing blackheads and whiteheads can remove them, but it can also damage the skin. Doing so increases the risk of causing or transmitting infection and scarring, as well as potentially pushing any infection deeper into the skin. Comedo extractors are used with careful hygiene in beauty salons and by dermatologists, usually after using steam or warm water.

Complementary medicine options for acne in general have not been shown to be effective in trials. These include aloe vera, pyridoxine (vitamin B6), fruit-derived acids, kampo (Japanese herbal medicine), ayurvedic herbal treatments and acupuncture.

Some acne treatments target infection specifically, but there are treatments that are aimed at the formation of comedones as well. Others remove the dead layers of the skin and may help clear blocked pores.

Dermatologists can often extract open comedones with minimal skin trauma, but closed comedones are more difficult. Laser treatment for acne might reduce comedones, but dermabrasion and laser therapy have also been known to cause scarring.

Macrocomedones (1 mm or larger) can be removed by a dermatologist using surgical instruments or cauterized with a device that uses light. The acne drug isotretinoin can cause severe flare-ups of macrocomedones, so dermatologists recommend removal before starting the drug and during treatment.

Some research suggests that the common acne medications, retinoids and azelaic acid, are beneficial and do not cause increased pigmentation of the skin.

Severe acne usually indicates the necessity of prescription medication to treat the pimples. Prescription medications used to treat acne and pimples include isotretinoin, which is a retinoid. Historically, antibiotics such as tetracyclines and erythromycin were prescribed. While they were more effective than topical applications of benzoyl peroxide, the bacteria eventually grew resistant to the antibiotics and the treatments became less and less effective. Also, antibiotics had more side effects than topical applications, such as stomach cramps and severe discoloration of teeth. Common antibiotics prescribed by dermatologists include doxycycline and minocycline. For more severe cases of acne dermatologists might recommend accutane, a retinoid that is the most potent of acne treatments. However, accutane can cause various side effects including vomiting, diarrhea, and birth defects if taken during pregnancy.

Common over-the-counter medications for pimples are benzoyl peroxide and/or salicylic acid and antibacterial agents such as triclosan. Both medications can be found in many creams and gels used to treat acne (acne vulgaris) through topical application. Both medications help skin slough off more easily, which helps to remove bacteria faster. Before applying them the patient needs to wash his or her face with warm water and dry. A cleanser may also be used for that purpose. Acne rosacea is not caused by bacterial infection. It is commonly treated with tretinoin. A regimen of keeping the affected skin area clean plus the regular application of these topical medications is usually enough to keep acne under control, if not at bay altogether. The most common product is a topical treatment of benzoyl peroxide, which has minimal risk apart from minor skin irritation that may present similar as a mild allergy. Recently nicotinamide (vitamin B), applied topically, has been shown to be more effective in treatment of pimples than antibiotics such as clindamycin. Nicotinamide is not an antibiotic and has no side effects typically associated with antibiotics. It has the added advantage of reducing skin hyperpigmentation which results in pimple scars.

No treatment of seborrheic keratoses is necessary, except for aesthetic reasons. Since a slightly increased risk of localized infection caused by picking at the lesion has been described, if a lesion becomes itchy or irritated by clothing or jewelry, a surgical excision is generally recommended.

Small lesions can be treated with light electrocautery. Larger lesions can be treated with electrodesiccation and curettage, shave excision, or cryosurgery. When correctly performed, removal of seborrheic keratoses will not cause much visible scarring except in persons with dark skin tones.

These lesions generally do not require treatment. If they are cosmetically unappealing or are subject to bleeding angiomas may be removed by electrocautery, a process of destroying the tissue by use of a small probe with an electric current running through it. Removal may cause scarring. More recently pulsed dye laser or intense pulsed light (IPL) treatment has also been used.

Future treatment based on a locally acting inhibitor of MEK1 and Cyclin E1 could possibly be an option. A natural MEK1 inhibitor is myricetin

Oil production in the sebaceous glands increases during puberty, causing comedones and acne to be common in adolescents. Acne is also found premenstrually and in women with polycystic ovarian syndrome. Smoking may worsen acne.

Oxidation rather than poor hygiene or dirt causes blackheads to be black. Washing or scrubbing the skin too much could make it worse, by irritating the skin. Touching and picking at comedones might cause irritation and spread infection. It is not clear what effect shaving has on the development of comedones or acne.

Some, but not all, skin products might increase comedones by blocking pores, and greasy hair products (like pomades) can worsen acne. Skin products that claim to not clog pores may be labeled noncomedogenic or non-acnegenic. Make-up and skin products that are oil-free and water-based may be less likely to cause acne. It is not known whether dietary factors or sun exposure make comedones better, worse or have no effect.

A hair that does not emerge normally can also block the pore and cause a bulge or lead to infection (causing inflammation and pus).

Genes may play a role in the chances of developing acne. Comedones may be more common in some ethnic groups. People of recent African descent may experience more inflammation in comedones, more comedonal acne, and earlier onset of inflammation.

Solar purpura (also known as "Actinic purpura," and "Senile purpura") is a skin condition characterized by large, sharply outlined, 1- to 5-cm, dark purplish-red ecchymoses appearing on the dorsa of the forearms and less often the hands.

The condition is most common in elderly people of European descent. It is caused by sun-induced damage to the connective tissue of the skin.

No treatment is necessary. The lesions typically fade over a period of up to 3 weeks.

Nevus comedonicus (also known as a "comedo nevus") is characterized by closely arranged, grouped, often linear, slightly elevated papules that have at their center keratinous plugs resembling comedones.

Liver spots (also known as age spot, solar lentigo, "lentigo senilis", "old age spot", "senile freckle") are es on the skin associated with aging and exposure to ultraviolet radiation from the sun. They range in color from light brown to red or black and are located in areas most often exposed to the sun, particularly the hands, face, shoulders, arms and forehead, and the scalp if bald.

The spots derive their name from the fact that they were once incorrectly believed to be caused by liver problems, but they are physiologically unrelated to the liver, save for a similar color. From the age of 40 onward the skin is less able to regenerate from sun exposure, and liver spots are very common in this age group, particularly in those who spend time in the sun.

In the overwhelming majority of cases, liver spots pose no threat and require no treatment, though they occasionally have been known to obscure the detection of skin cancer. However, despite being a benign condition, liver spots are sometimes considered unsightly and some people choose to have them removed. This can be done by electrosurgery, laser treatment, cryotherapy, or the use of depigmentation agents, such as hydroquinone, tretinoin, topical cysteamine, azelaic acid or alpha hydroxy acids.

In most patients, the number and size of cherry angiomas increases with advancing age. They are harmless, having no relation to cancer at all.

Many conditions affect the human integumentary system—the organ system covering the entire surface of the body and composed of skin, hair, nails, and related muscle and glands. The major function of this system is as a barrier against the external environment. The skin weighs an average of four kilograms, covers an area of two square meters, and is made of three distinct layers: the epidermis, dermis, and subcutaneous tissue. The two main types of human skin are: glabrous skin, the hairless skin on the palms and soles (also referred to as the "palmoplantar" surfaces), and hair-bearing skin. Within the latter type, the hairs occur in structures called pilosebaceous units, each with hair follicle, sebaceous gland, and associated arrector pili muscle. In the embryo, the epidermis, hair, and glands form from the ectoderm, which is chemically influenced by the underlying mesoderm that forms the dermis and subcutaneous tissues.

The epidermis is the most superficial layer of skin, a squamous epithelium with several strata: the stratum corneum, stratum lucidum, stratum granulosum, stratum spinosum, and stratum basale. Nourishment is provided to these layers by diffusion from the dermis, since the epidermis is without direct blood supply. The epidermis contains four cell types: keratinocytes, melanocytes, Langerhans cells, and Merkel cells. Of these, keratinocytes are the major component, constituting roughly 95 percent of the epidermis. This stratified squamous epithelium is maintained by cell division within the stratum basale, in which differentiating cells slowly displace outwards through the stratum spinosum to the stratum corneum, where cells are continually shed from the surface. In normal skin, the rate of production equals the rate of loss; about two weeks are needed for a cell to migrate from the basal cell layer to the top of the granular cell layer, and an additional two weeks to cross the stratum corneum.

The dermis is the layer of skin between the epidermis and subcutaneous tissue, and comprises two sections, the papillary dermis and the reticular dermis. The superficial papillary dermis with the overlying rete ridges of the epidermis, between which the two layers interact through the basement membrane zone. Structural components of the dermis are collagen, elastic fibers, and ground substance. Within these components are the pilosebaceous units, arrector pili muscles, and the eccrine and apocrine glands. The dermis contains two vascular networks that run parallel to the skin surface—one superficial and one deep plexus—which are connected by vertical communicating vessels. The function of blood vessels within the dermis is fourfold: to supply nutrition, to regulate temperature, to modulate inflammation, and to participate in wound healing.

The subcutaneous tissue is a layer of fat between the dermis and underlying fascia. This tissue may be further divided into two components, the actual fatty layer, or panniculus adiposus, and a deeper vestigial layer of muscle, the panniculus carnosus. The main cellular component of this tissue is the adipocyte, or fat cell. The structure of this tissue is composed of septal (i.e. linear strands) and lobular compartments, which differ in microscopic appearance. Functionally, the subcutaneous fat insulates the body, absorbs trauma, and serves as a reserve energy source.

Conditions of the human integumentary system constitute a broad spectrum of diseases, also known as dermatoses, as well as many nonpathologic states (like, in certain circumstances, melanonychia and racquet nails). While only a small number of skin diseases account for most visits to the physician, thousands of skin conditions have been described. Classification of these conditions often presents many nosological challenges, since underlying etiologies and pathogenetics are often not known. Therefore, most current textbooks present a classification based on location (for example, conditions of the mucous membrane), morphology (chronic blistering conditions), etiology (skin conditions resulting from physical factors), and so on. Clinically, the diagnosis of any particular skin condition is made by gathering pertinent information regarding the presenting skin lesion(s), including the location (such as arms, head, legs), symptoms (pruritus, pain), duration (acute or chronic), arrangement (solitary, generalized, annular, linear), morphology (macules, papules, vesicles), and color (red, blue, brown, black, white, yellow). Diagnosis of many conditions often also requires a skin biopsy which yields histologic information that can be correlated with the clinical presentation and any laboratory data.

A seborrheic keratosis, also known as seborrheic verruca, basal cell papilloma, or a senile wart, is a non-cancerous (benign) skin tumour that originates from cells in the outer layer of the skin (keratinocytes). Like liver spots, seborrheic keratoses are seen more often as people age.

The tumours (also called lesions) appear in various colours, from light tan to black. They are round or oval, feel flat or slightly elevated, like the scab from a healing wound, and range in size from very small to more than across. They can often come in association with other skin conditions, including basal cell carcinoma. Sometimes seborrheic keratosis and basal cell carcinoma occur at the same location, and sometimes seborrheic keratosis progresses to basal cell carcinoma. At clinical examination the differential diagnosis include warts and melanoma. Because only the top layers of the epidermis are involved, seborrheic keratoses are often described as having a "pasted on" appearance. Some dermatologists refer to seborrheic keratoses as "seborrheic warts", because they resemble warts, but strictly speaking the term "warts" refers to lesions that are caused by human papillomavirus.

The condition is usually self-limiting, and thus not indicated for surgery.

Differently from the melanotic nevi and the verrucous nevi on the skin, age spots change with time in color and in shape. Misrepair-accumulation aging theory proposes a hypothesis on the development of age spots. Firstly, the development of a flat spot is a result of accumulation of aged basal cells. When the skin is aged, some aged cells that contain lipofuscin bodies cannot be removed. An aged cell will affect the functionality of the local tissue and promote the aging of its neighbor cells. By a feedback loop, more and more neighbor cells become aged and lipofuscin-containing. They aggregate and form a spot with an irregular shape. Secondly, protruding of a flat spot is a result of the death of aged cells in the spot and release of lipofuscin bodies. Isolation of the un-digestible lipofuscin bodies in a fibrotic capsule is essential for maintaining the structural integrity of the tissue. Successive encapsulation of dead cells and lipofuscin bodies results in the growth of a spot in three dimensions. The dense lipofuscin bodies in the capsule make a protruding spot soft and dark in color.

Radiation burns should be covered by a clean, dry dressing as soon as possible to prevent infection. Wet dressings are not recommended. The presence of combined injury (exposure to radiation plus trauma or radiation burn) increases the likelihood of generalized sepsis. This requires administration of systemic antimicrobial therapy.

A dilated pore, also known as a dilated pore of Winer, is a cutaneous condition characterized by a solitary, prominent, open comedo on the face or upper trunk of an individual. They can occur on either young or elderly individuals. They are benign; however, they can be considered unsightly. The only curative method of removal is a punch excision, usually 1–3 mm. Lasers and other superficial means of removal have proven to be ineffective.

Radiation burns are caused by exposure to high levels of radiation. Levels high enough to cause burn are generally lethal if received as a whole-body dose, whereas they may be treatable if received as a shallow or local dose.

Medical treatment of gynecomastia is most effective when done within the first two years after the start of male breast enlargement. Selective estrogen receptor modulators (SERMs) such as tamoxifen, raloxifene, and clomifene may be beneficial in the treatment of gynecomastia but are not approved by the Food and Drug Administration for use in gynecomastia. Clomifene seems to be less effective than tamoxifen or raloxifene. Tamoxifen may be used for painful gynecomastia in adults. Aromatase inhibitors (AIs) such as anastrozole have been used off-label for cases of gynecomastia occurring during puberty but are less effective than SERMs. A few cases of gynecomastia caused by the rare disorders aromatase excess syndrome and Peutz–Jeghers syndrome have responded to treatment with AIs such as anastrozole. Androgens/anabolic steroids may be effective for gynecomastia. Testosterone itself may not be suitable to treat gynecomastia as it can be aromatized into estradiol, but non-aromatizable androgens like topical androstanolone (dihydrotestosterone) can be useful.

Mild cases of gynecomastia in adolescence may be treated with advice on lifestyle habits such as proper diet and exercise with reassurance. In more severe cases, medical treatment may be tried including surgical intervention.

Even though more studies are necessary for an efficient evaluation of the role played by zinc in senile osteoporosis, doctors recommend a proper supplementation of dietary zinc.

Replacement estrogen has proved to be an efficient way to combat the loss of bone mass in women when such treatment is started in the menopausal stage of their lives. John R. Lee, a Harvard graduate who wrote a book on the subject, came to the conclusion that by adding supplementation with natural progesterone to an existing natural osteoporosis treatment program, bone density was increased every year by 3-5% until it stabilized at the bone density levels expected for a 35-year-old woman, this after studies in 100 women between 38 and 83 with an average of 62 years old.

No drug has been shown to be able to arrest or slow down the process of this condition. There is promise that two drugs, tafamidis and diflunisal, may improve the outlook, since they were demonstrated in randomized clinical trials to benefit patient affected by the related condition FAP-1 otherwise known as transthyretin-related hereditary amyloidosis. Permanent pacing can be employed in cases of symptomatic slow heart rate (bradycardia). Heart failure medications can be used to treat symptoms of difficulty breathing and congestion.

While PEX itself is untreatable as of 2011, it is possible for doctors to minimize the damage to vision and to the optic nerves by the same medical techniques used to prevent glaucoma.

- Eyedrops. This is usually the first treatment method. Eyedrops can help reduce intraocular pressure within the eye. The medications within the eyedrops can include beta blockers (such as levobunolol or timolol) which slow the production of the aqueous humor. And other medications can increase its outflow, such as prostaglandin analogues (e.g. latanoprost). And these medicines can be used in various combinations. In most cases of glaucoma, eyedrops alone will suffice to solve the problem.

- Laser surgery. A further treatment is a type of laser therapy known as trabeculoplasty in which a high-energy laser beam is pointed at the trabecular meshwork to cause it to "remodel and open" and improve the outflows of the aqueous humor. These can be done as an outpatient procedure and take less than twenty minutes. One report suggests this procedure is usually effective.

- Eye surgery. Surgery is the treatment method of last resort if the other methods have not worked. It is usually effective at preventing glaucoma. Eye surgery on PEX patients can be subject to medical complications if the fibers which hold the lens have become weakened because of a buildup from the flakes; if the lens-holding fibers have weakened, then the lens may become loose, and complications from eye surgery may result. In such cases, it is recommended that surgeons act quickly to repair the phacodonesis before the lenses have dropped. A surgeon cuts an opening in the white portion of the eye known as the sclera, and removes a tiny area of the trabecular meshwork which enables the aqueous humor to discharge. This lowers the internal pressure within the eye and lessens the chance of future damage to the optic nerve. Cases with pseudophacodonesis and dislocated IOL have been increasing in number, according to one report. In cataract surgery, complications resulting from PEX include capsular rupture and vitreous loss.

- Drug therapy. There are speculations that if genetics plays a role in PEX, and if the specific genes involved can be identified, that possibly drugs can be developed to counteract these mutations or their effects. But such drugs have not been developed as of 2011.

Patients should continue to have regular eye examinations so that physicians can monitor pressure levels and check whether medicines are working.

Acneiform eruptions are caused by changes in the pilosebaceous unit.

- Acne aestivalis (Mallorca acne)

- Acne conglobata

- Acne cosmetica (cosmetic acne)

- Acne fulminans (acute febrile ulcerative acne)

- Acne keloidalis nuchae (acne keloidalis, dermatitis papillaris capillitii, folliculitis keloidalis, folliculitis keloidis nuchae, nuchal keloid acne)

- Acne mechanica

- Acne medicamentosa

- Acne miliaris necrotica (acne varioliformis)

- Acne vulgaris (acne simplex)

- Acne with facial edema (solid facial edema)

- Blepharophyma

- Erythrotelangiectatic rosacea (erythematotelangiectatic rosacea, vascular rosacea)

- Excoriated acne ("acne excoriée des jeunes filles", Picker's acne)

- Glandular rosacea

- Gnathophyma

- Gram-negative rosacea

- Granulomatous facial dermatitis

- Granulomatous perioral dermatitis

- Halogen acne

- Hidradenitis suppurativa (acne inversa, pyoderma fistulans significa, Verneuil's disease)

- Idiopathic facial aseptic granuloma

- Infantile acne

- Lupoid rosacea (granulomatous rosacea, micropapular tuberculid, rosacea-like tuberculid of Lewandowsky)

- Lupus miliaris disseminatus faciei

- Metophyma

- Neonatal acne (acne infantum, acne neonatorum, neonatal cephalic pustulosis)

- Occupational acne

- Oil acne

- Ocular rosacea (ophthalmic rosacea, ophthalmorosacea)

- Otophyma

- Periorificial dermatitis

- Persistent edema of rosacea (chronic upper facial erythematous edema, Morbihan's disease, rosaceous lymphedema)

- Phymatous rosacea

- Pomade acne

- Papulopustular rosacea (inflammatory rosacea)

- Perifolliculitis capitis abscedens et suffodiens (dissecting cellulitis of the scalp, dissecting folliculitis, perifolliculitis capitis abscedens et suffodiens of Hoffman)

- Perioral dermatitis

- Periorbital dermatitis (periocular dermatitis)

- Pyoderma faciale (rosacea fulminans)

- Rhinophyma

- Rosacea (acne rosacea)

- Rosacea conglobata

- Synovitis–acne–pustulosis–hyperostosis–osteomyelitis syndrome (SAPHO syndrome)

- Steroid rosacea

- Tar acne

- Tropical acne