• Most rashes produced by makeup are irritations not allergies.
• If a particular product causes irritation, then avoid it.
• Makeup and cosmetics are complex mixtures of substances, any of which could produce irritation and allergies.
• Reactions to cosmetics are rare.
• Other skin problems like seborrheic dermatitis, atopic dermatitis, and rosacea may be confused with cosmetic sensitivities.
• Once you are allergic to a particular chemical the sensitivity lasts forever.

Cosmetics are substances applied to the surface of the skin (moisturizers and makeup), hair (shampoos and conditioners), or nails (polish and lacquer) designed to temporarily alter one's appearance. Cosmetics do not biologically alter the structure or function of the skin, hair, or nails. They are often a complex mixture of perfumes, emulsifiers, sunscreens, pigments, metals, resins, and preservatives, as well as a variety of inert materials. They also frequently contain an array of exotic botanical substances (for example, essential oils) for which the manufacturer may ascribe some obscure benefit. Generally, they are meant to be removed after use. They should be distinguished from permanent makeup, which is essentially a tattoo composed of pigment placed into the deeper layers of the skin with a needle. The FDA and the USDA are responsible for administering laws involving the safety and purity of cosmetics. Revenue of the U.S. cosmetics industry will be about $59 billion in 2014!

Untoward reactions to cosmetics seem to be rare considering their extensive use. Documented allergic sensitivity is even rarer. This may be partly due to the fact that affected individuals may just stop using the offending product rather than complain about it to a professional. Cosmetics may irritate the skin directly (by far the most common type of reaction) or induce an immune-mediated allergic response. Usually irritation would occur the first time a cosmetic is applied, as opposed to an allergic reaction that would require repeated exposures. Some individuals have extremely sensitive skin that seems to be intolerant to most cosmetics. Individuals with rosacea seem to be intolerant to many cosmetics and makeup brands.

Since cosmetics are most commonly applied to the female face, this site is most commonly involved in cosmetic skin reactions and inflammatory dermatitis. The rash produced by such a reaction often appears as a scaling, dry, itchy red area, an eczematous dermatitis, usually confined to the area where the cosmetic was applied (for example, the eyelids may become irritated after applying eye shadow). Occasionally, cosmetic skin reactions can appear as hives (welts). This type of hives (contact urticarial) can be either allergic or nonallergic. It is often very difficult to distinguish on the basis of appearance whether the reaction is allergic or irritant. Sometimes there may be a stinging sensation soon after the offending cosmetic is applied, or the reaction can be delayed for a day or two. Less commonly, reactions may appear as blackheads, folliculitis, hives, and darkened skin.

The ingredients in a cosmetic are required to be listed on the label in order of decreasing quantity. Any ingredient could potentially produce a reaction, but certain ingredients seem to be more likely to cause problems. The use of the terms hypoallergenic, pure, and natural on the label have very little scientific meaning and are essentially marketing jargon. Cosmetics that use the term organic must be manufactured according to certain USDA criteria that have little to do with consumer safety.

Dermatologists have the most experience in dealing with makeup and cosmetic intolerance.

If a cosmetic is being considered as a potential cause of a reaction, the patient can perform a "use" test over three or four days by repeatedly applying the substance to the same site on forearm skin. If a reaction appears, further types of allergy testing can be performed by a health care professional to determine the precise identity of the offending substance in the cosmetic mixture. One can then avoid the product as well as avoiding further exposure to the same allergenic component in other cosmetic products.

There are a number of common skin diseases that are likely to be confused with cosmetic rashes. Perhaps the best way to distinguish these is to avoid using the particular cosmetic in question for two or three weeks. If the rash resolves and then recurs when the cosmetic is used again, it is reasonably likely that the problem is the cosmetic. If the rash persists, on the other hand, then it is probably due to a skin disease like seborrheic dermatitis, atopic dermatitis, or some other problem.

Mild cosmetic reactions usually will resolve with no treatment as long as the offending product is avoided. More serious reactions often respond to treatment with 1% hydrocortisone cream that can be purchased without a prescription. If this fails, then it will be necessary to visit a health care professional for a stronger topical steroid.

If the source of a cosmetic reaction is an irritant chemical, then it seems likely that by avoiding that substance, when present in other products, would be prudent. The immediate reaction subsides in a few days. A dermatologist can help decide which ingredient on the label is likely to be a problem. If a reaction is due to an allergy to an ingredient that was documented by patch testing, then it is very important to avoid that particular ingredient by carefully perusing the cosmetic labels. Sometimes this can be challenging because certain additives in beauty products may have a number of brand names. Although the immediate allergic reaction to the chemical will resolve within a few weeks, the propensity to react on re-exposure always exists.

The best way to avoid a cosmetic reaction is to avoid cosmetics entirely. Since this is impractical, then using cosmetics with a minimal number of ingredients might be helpful. Some cosmetics may contain labeling using the terms unscented or fragrance-free. This distinction can be important because unscented products often contain fragrance chemicals that disguise odor whereas fragrance-free products are supposed to be devoid of fragrances entirely.

There is no government body that certifies the safety or non-allergenicity of cosmetics or makeup. From the FDA's web site: "FDA does not have the legal authority to approve cosmetic products and ingredients (other than color additives) before they go on the market. We also do not have a list of tests required for any particular cosmetic product or ingredient. However, a manufacturer or distributor of a cosmetic is legally responsible for ensuring that a marketed product is safe when consumers use it according to the directions in the labeling or in the customary or expected way. FDA can take action against the manufacturer of a cosmetic on the market if we have reliable information to show that a cosmetic does not meet the legal requirement for safety."