Topical medications are medications applied directly to the skin. They are a mainstay of treating skin disorders. Systemic medications are taken by mouth or given by injection and are distributed throughout the body. Rarely, when a high concentration of a medication is needed at the affected area, a doctor injects the medication just under the skin (intradermal injection).
For certain topical treatments, successful therapy may also depend on
The vehicle (the inactive ingredient in which the medication is delivered to the skin)
The type of dressing used
Topical Preparations
The active ingredient, or medication, in a topical preparation is mixed with an inactive ingredient (called the vehicle). The vehicle determines the consistency of the product (for example, thick and greasy or light and watery) and whether the active ingredient remains on the surface or penetrates the skin. Depending on the vehicle used, the same medication can be placed in
Ointments
Creams
Lotions
Baths and soaks
Foams
Solutions
Powders
Gels
In addition, many preparations are available in different strengths (concentrations). Choice of vehicle depends on where the medication will be applied, how it will look, and how convenient it is to apply and leave on.
Ointments (such as petroleum jelly) are oily and contain very little water. They can be messy, greasy, and difficult to wash off. Ointments are most appropriate when the skin needs lubrication or moisture. Ointments are usually better than creams at delivering active ingredients into the skin. A given concentration of a medication is more potent in an ointment than in a cream. Ointments are less irritating than creams and much less irritating than gels, lotions, and solutions for open wounds such as erosions or ulcers. Ointments work best when applied after bathing or after dampening the skin with water.
Creams, the most commonly used preparations, are emulsions of oil in water, meaning they are primarily water with an oil component. (An ointment is the opposite, some water mixed mostly with oil.) Creams are easy to apply and appear to vanish when rubbed into the skin. They are relatively nonirritating.
Lotions are similar to creams but contain more water. They are actually suspensions of finely dispersed, powdered material in a base of water or oil and water. They are less effective than ointments, creams, and gels at delivering medications and are considered of lower potency for a given concentration of medication. However, lotions have a number of beneficial effects. They are easy to apply to hairy skin, and they are particularly useful for cooling or drying inflamed or oozing lesions, such as those caused by contact dermatitis, athlete's foot (tinea pedis), or jock itch (tinea cruris).
Baths and soaks are used when treatment must be applied to large areas of the body. This technique is often used in the form of sitz baths as an over-the-counter (OTC) treatment of a mild skin problem such as hemorrhoids. Baths are not often used to apply potent prescription medications because of difficulties controlling the amount of medication delivered.
Foams are aerosol preparations (liquids stored under pressure with a propellant so that the mixture can be dispensed) that use a base of alcohol or something soothing to the skin (called an emollient). They are rapidly absorbed into the skin and are often used in hair-covered areas of the body.
Solutionspsoriasis or seborrheic dermatitis
Powders are dried forms of substances that are used to protect areas where skin rubs against skin—for instance, between the toes or buttocks, in the armpits or groin, or under the breasts. Powders are used on skin that has been softened and damaged by moisture (macerated). They may be mixed with active medications such as antifungals.
Gels are water-based or alcohol-based substances thickened without oil or fat. The skin does not absorb gels as well as it absorbs preparations containing oil or fat. Thus, they are often most effective for conditions that require slow absorption, such as acne, rosacea, and psoriasis of the scalp. Gels tend to be quite irritating on open wounds and diseased skin.
Did You Know...
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Types of Topical Medications
Topical medications can be divided into several overlapping categories:
Moisturizing agents (emollients)
Cleansing agents
The principal cleansing agents are soaps, detergents, and solvents (a liquid substance capable of dissolving other substances). Soap is the most popular cleanser, but detergents are used as well. Soaps are cleansing and emulsifying agents containing some type of fat or lye, whereas detergents are made from petroleum products. Certain soaps dry the skin, but others have a creamy base that is less drying.
Because baby shampoos are excellent cleansing agents and are usually gentle to the skin, they are good for cleansing wounds, cuts, abrasions, and areas around the eyes. Also, people who have psoriasis, eczema, and other scaling diseases can use baby shampoos to wash away dead scaly skin. Oozing lesions, however, should generally be cleansed only with water or gentle soaps because detergents and harsher soaps can irritate the area.
Water is the main solvent for cleansing. Other solvents include petroleum jelly, which can cleanse the skin of material that cannot be dissolved with soap and water, such as tar. Small amounts of alcohol can safely be used to cleanse the skin before injections or blood drawing. Alcohol gels are useful as hand sanitizers for routine hand hygiene when handwashing is not possible. Other solvents, such as acetone (nail polish remover), gasoline, and paint thinner, are rarely used for skin cleansing. These solvents dissolve the skin's natural oils, causing significant drying and irritation. They may also be absorbed through the skin, resulting in poisoning.
Protective agents
Many different kinds of preparations help protect the skin. Oils and ointments supply an oil-based barrier that can help protect scraped or irritated skin and retain moisture. Powders may protect skin that rubs against skin or clothing. Synthetic hydrocolloid dressings protect pressure sores (bedsores) and other areas of raw skin. Sunscreens and sunblocks reflect, absorb, or filter out harmful ultraviolet light.
Moisturizing agents (emollients)
Drying agents
Excessive moisture in areas where skin rubs against skin can cause irritation and skin breakdown (maceration), particularly in body folds where the environment tends to be warmer and moister. The areas most commonly affected are between the toes or buttocks, in the armpits or groin, and under the breasts and abdominal skin folds. These warm moist areas also provide fertile breeding grounds for infections, especially with fungi and bacteria.
Cornstarch and talcum powder are the most commonly used drying agents. These powders absorb moisture from the skin surface. Most of the many talcum preparations vary only in their scents and packaging. Talcum powder is more effective than cornstarch but is no longer used in baby powders, because it can cause granulomas (a type of chronic inflammation) in the lungs when inhaled. Using talcum powder in the female genital area is not recommended because of concerns of possible risk of cancer. Cornstarch is a good drying agent but can sometimes lead to fungal infections. Superabsorbent powders (extremely absorbent powders) are occasionally required to dry very moist areas, such as in the groin or armpits.
Solutions containing aluminum salts are drying agents commonly found in OTC antiperspirants. Prescription doses of aluminum salts are available to treat excessive sweating.
Astringentseczema, oozing skin lesions, and pressure sores. Witch hazel is also a popular OTC astringent.
Anti-itch agents
Antihistamines, which block certain types of allergic reactions
Anti-inflammatory agents
Corticosteroids are the main topical medications used to relieve inflammation (swelling, itching, and redness) of the skin. Corticosteroids are most effective for rashes caused by allergic or inflammatory reactions to things such as poison ivy, metals, cloth, drugs, eczema, and many others. Because they lower resistance to bacterial and fungal infections and inhibit wound healing, corticosteroids usually should not be used on infected areas or wounds. For acne-like disorders, topical corticosteroids tend to not work very well and sometimes instead induce an acne-like eruption. Corticosteroids are sometimes mixed with antifungals to help reduce redness and itching while simultaneously eradicating the fungus.
Corticosteroids should be used with caution on areas where the skin is thin, such as the face, armpits, and genitals, and on areas of natural skin-to-skin contact, such as the armpits and groin. Doctors usually use low-potency corticosteroids on these sensitive areas for no more than a few days to a week. Prolonged use (more than 1 month) in any area can cause skin breakdown, stretch marks, acne-like eruptions, and sometimes an allergic skin reaction (allergic contact dermatitis) to the corticosteroid itself. Perioral dermatitis (a red, bumpy rash around the mouth and chin) and sometimes periorbital dermatitis (a rash around the eyes) occurs as a side effect more commonly with mid-potency or high-potency formulations used on the face and less commonly with low-potency formulations. High-potency formulations may inhibit adrenal gland functions when used in children, when used over large areas of skin, or when used for long periods of time, especially if used under occlusive (airtight and watertight) dressings.
Another way to deliver a strong dose is to apply a thin plastic film, such as household plastic wrap, over the topical corticosteroid (occlusive dressing). The plastic wrap increases the medication's absorption and effectiveness and is usually left on overnight. Such dressings are usually reserved for disorders such as severe psoriasis and eczema. Risks of using corticosteroids under an occlusive dressing include development of skin thinning (atrophy), stretch marks (striae), dilated red blood vessels on the surface of the skin (telangiectasias), prickly heat (miliaria), acne-like eruption, and bacterial or fungal infections.
Several allegedly anti-inflammatory herbal products—among the most popular are chamomile and calendula—are commonly used in commercial products, but their effectiveness has not been well established. Herbal and "natural" products are often not standardized and commonly cause allergic and irritant reactions of the skin.
Tar preparations are noncorticosteroid anti-inflammatory agents, which are byproducts of coal manufacturing. They slow skin cell division and are useful in treating disorders that cause excessive skin production (scaling) such as psoriasis. Side effects include irritation, inflammation of follicles (folliculitis), staining of clothes and furniture, and sensitivity to sunlight (photosensitization). They should not be used on infected skin.
Anti-infective agents
Viruses, bacteria, fungi, and parasites can infect the skin. By far, the best way to prevent such infections is by carefully washing the skin with soap and water. Stronger disinfecting agents are commonly used by nurses and doctors to disinfect their hands to prevent spreading infections to patients. Antibacterial preparations or "preps" are used on the skin before surgery to lower the number of bacteria on the skin and thereby prevent postoperative infections.
Once a skin infection has occurred, it may be treated with topical or systemic medications depending on the severity and type of infection diagnosed or suspected. Topical anti-infective agents include antibiotics, antifungals, and insecticides.
Topical antibioticsacneclindamycin, or erythromycin are used for rosaceaimpetigo (a staphylococcal infection of the skin).
skin biopsy site and to prevent infection in scrapes, minor burns, and abrasions. Bacitracin and polymyxincontact dermatitis). Petrolatum is as effective as these antibiotics and does not cause such an allergic reaction.
Topical antifungals work quite well for treating a wide variety of fungal infections of the skin (such as ringworm and athlete's foot
Insecticideslice infestations and scabies.
Nonantibiotic topical antiseptics
psoriasis or seborrheic dermatitis.
Healing wounds should usually not be treated with topical antiseptics other than silver because they are irritating and tend to kill fragile regrowth (granulation tissue).
Keratolytics
in varying concentrations is used to treat psoriasis, seborrheic dermatitis, acne, and warts. Side effects are common and include burning, irritation, and, if large areas of skin are covered, reactions elsewhere in the body (systemic reactions) caused by absorbing the salicylic acid. Salicylic acid is rarely used in children and infants, who are most susceptible to systemic reactions, except in very low concentrations and for brief periods of time.
can be used to moisturize, soothe itching, and reduce scaling. It is commonly used to treat excessive skin buildup on the soles of the feet (plantar keratodermas and calluses), keratosis pilaris (dry bumps on thighs and back of arms in people with allergies), and other dry skin conditions such as ichthyosis. Side effects are irritation and burning. Urea should not be applied to large areas of skin.
Dressings
Dressings protect open wounds, facilitate healing, increase medication absorption, and protect clothing.
There are 2 kinds of dressings:
Nonocclusive (air can reach the wound)
Occlusive (wounds are covered and sealed from contact with air)
Nonocclusive dressings
The most common nonocclusive dressings are gauze dressings. They allow as much air as possible to reach the wound while the wound is covered, and allow the wound to dry.
Wet-to-dry dressings are nonocclusive dressings wetted with solution, usually saline, that are used to help cleanse and remove (debride) thickened, crusted, or dead tissue. The dressings are applied wet and removed after the solution has dried. The dried materials stick to the dressing.
Occlusive dressings
stasis dermatitis). Hydrocolloid dressings draw out fluid from the skin and form a gel and are used to speed the healing of skin ulcers.
Occlusive dressings are sometimes applied over corticosteroids for treating severe psoriasis, atopic dermatitis, skin lesions of lupus erythematosus, and chronic hand dermatitis, among other conditions.
Other occlusive dressings are used to protect and help heal burns. Doctors have also found that other types of open wounds heal faster and more completely when kept moist and kept under an occlusive dressing. These dressings help maintain a proper level of moisture and provide a framework on which new skin can regrow. Such dressings include sophisticated commercial products as well as plain petroleum jelly or an antibiotic ointment under a bandage.
Special silicone dressings are sometimes used for keloids (scar tissue).
