Prickly heat can be prevented by avoiding activities that induce sweating, using air conditioning to cool the environment, wearing light clothing and in general, avoiding hot and humid weather. Frequent cool showers or cool baths with mild soap can help to prevent heat rash.

Treatment differs according to what rash a patient has been diagnosed with. Common rashes can be easily remedied using steroid topical creams (such as hydrocortisone) or non-steroidal treatments. Many of the medications are available over the counter in the United States.

The problem with steroid topical creams i.e. hydrocortisone; is their inability to penetrate the skin through absorption and therefore not be effective in clearing up the affected area, thus rendering the hydrocortisone almost completely ineffective in all except the most mild of cases.

The primary remedy for miliaria is to wear lighter clothing, move to a cooler climate, or otherwise avoid overheating one's body. The immediate treatment of the involved skin areas involves the use of a soothing ointment such as calamine lotion.

Medical assistance should be sought for the first episode of a rash with the appearance of miliaria. The differential diagnosis includes several conditions that an experienced practitioner should be able to recognise and may require treatment distinct from the usual measures taken for miliaria. In most cases the rash of miliaria will resolve without intervention. However, severe cases can last for weeks and cause significant disability. General measures should be recommended for all patients, including moving to an air-conditioned environment if possible, avoiding sweat-provoking activities and occlusive clothing, and taking frequent cool showers.

It has been suggested that the use of topical antibacterials (including antibacterial soaps) may shorten the duration of symptoms in miliaria rubra even in the absence of obvious superinfection. Other topical agents that may reduce the severity of symptoms include anti-itch preparations such as calamine or menthol- or camphor-based preparations, and topical steroid creams. However, caution should be used with oil-based preparations (ointments and oily creams as opposed to water-based or aqueous lotions) that may increase blockage to the sweat glands and prolong duration of illness. Other agents have been investigated including supplemental vitamin A and C and vitamin A based medications, but it is worth noting that there is little scientific evidence supporting any of the above treatments in reducing the duration of symptoms or frequency of complications.

In most cases, doctors will recommend that any pimple-like blisters that may form should have the fluid drained out of them (either through in-office procedure or at home in a sterile environment) to avoid the rash from spreading underneath the skin, leading to an increased state of dermatitis. Left untreated, the blisters may spread and take on an increased red appearance, with the fluid inside increasing in viscosity. It is recommended by physicians to sanitize the infected area and then drain the blisters with a sterilized needle or lancet.

In most tropical areas the local dispensaries sell prickly heat powder, a talc admixture containing drying milk proteins (Labilin) and Triclosan to fight the infection. These include cooling menthol to help alleviate difficulty getting to sleep. This is an effective treatment—the powder stays on the skin longer and treats bacteria dispersed into bed linens, providing a reasonably dry refuge area for healing. Miliaria often covers large areas, and generous use of Cortisone may be contraindicated for reasons stated on package warnings. Regular talcum powder will not reduce the rash but can alleviate burning and itching.

In cases where the rash has developed into open blisters or pustular lesions a doctor should be consulted since more aggressive, medically monitored treatment may be required.

Common causes of rashes include:

- Food allergy

- Medication side effects

- Anxiety

- Allergies, for example to food, dyes, medicines, insect stings, metals such as zinc or nickel; such rashes are often called hives.

- Skin contact with an irritant

- Fungal infection, such as ringworm

- Balsam of Peru

- Reaction to vaccination

- Skin diseases such as eczema or acne

- Exposure to sun (sunburn) or heat

- Friction due to chafing of the skin

- Irritation such as caused by abrasives impregnated in clothing rubbing the skin. The cloth itself may be abrasive enough for some people

- Secondary syphilis

- Poor personal hygiene

Uncommon causes:

- Autoimmune disorders such as psoriasis

- Lead poisoning

- Pregnancy

- Repeated scratching on a particular spot

- Lyme Disease

- Scarlet fever

A maculopapular rash is a type of rash characterized by a flat, red area on the skin that is covered with small confluent bumps. It may only appear red in lighter-skinned people. The term "maculopapular" is a compound: "macules" are small, flat discolored spots on the surface of the skin; and "papules" are small, raised bumps. It is also described as erythematous, or red.

This type of rash is common in several diseases and medical conditions, including scarlet fever, measles, Ebola virus disease, rubella, secondary syphilis (Congenital syphilis, which is asymptomatic, the newborn may present this type of rash), erythrovirus (parvovirus B19), chikungunya (alphavirus), zika, and heat rash. It is also a common manifestation of a skin reaction to the antibiotic amoxicillin or chemotherapy drugs. Cutaneous infiltration of leukemic cells may also have this appearance. Maculopapular rash is seen in graft-versus-host disease (GVHD) developed after a hematopoietic stem cell transplant (bone marrow transplant), which can be seen within one week or several weeks after the transplant. In the case of GVHD, the maculopapular rash may progress to a condition similar to toxic epidermal necrolysis. In addition, this is the type of rash that some patients presenting with Ebola virus hemorrhagic (EBO-Z) fever will reveal but can be hard to see on dark skin people. It is also seen in patients with Marburg hemorrhagic fever, a filovirus not unlike Ebola.

This type of rash can be as a result of large doses of niacin or no-flush niacin (2000 – 2500 mg), used for the management of low HDL cholesterol.

This type of rash can also be a symptom of Sea bather's eruption. This stinging, pruritic, maculopapular rash affects swimmers in some Atlantic locales (e.g., Florida, Caribbean, Long Island). It is caused by hypersensitivity to stings from the larvae of the sea anemone (e.g., "Edwardsiella lineate") or the thimble jellyfish ("Linuche unguiculata"). The rash appears where the bathing suit contacts the skin.

This type of rash can also be a symptom of acute arsenic intoxication, appearing 2 weeks later.

Because the eruption is transient and self-limiting, no treatment is indicated.

Some sources claim that diaper rash is more common with cloth diapers. Others claim the material of the diaper is relevant insofar as it can wick and keep moisture away from the baby's skin, and preventing secondary "Candida" infection. However, there may not be enough data from good-quality, randomized controlled trials to support or refute disposable diaper use thus far. Furthermore, the effect of non-biodegradable diapers on the environment is a concerning matter for public policy.

The condition usually resolves on its own, and treatment is not required. Oral antihistamines or topical steroids may be used to decrease itching. Steroids do provide relief from itching, and improve the appearance of the rash, but they also cause the new skin that forms (after the rash subsides) to take longer to match the surrounding skin color. While no scarring has been found to be associated with the rash, scratching should be avoided. It's possible that scratching can make itching worse and an itch-scratch cycle may develop with regular scratching (that is, you itch more because you scratch, so you scratch more because you itch, and so on). Irritants such as soaps with fragrances, hot water, wool, and synthetic fabrics should be avoided. Lotions that help stop or prevent itching may also be helpful.

Direct sunlight makes the lesions resolve more quickly. According to this principle, medical treatment with ultraviolet light has been used to hasten resolution, though studies disagree whether it decreases itching or not. UV therapy is most beneficial in the first week of the eruption.

Oral erythromycin was effective in treating patients in one early trial, but a later study could not confirm these results. Since Human Herpes Virus 6 or Human Herpes Virus 7 has been hypothesized to be the cause, the antiviral drug Acyclovir may reduce length of duration and severity.

The most effective treatment, although not the most practical one, is to discontinue use of diapers, allowing the affected skin to air out. Another option is simply to increase the frequency of diaper changing. Thorough drying of the skin before diapering is a good preventive measure because it is the excess moisture, either from urine and feces or from sweating, that sets the conditions for a diaper rash to occur.

Both lyme disease and STARI can be treated with antibiotics, particularly doxycyclin.

The more poignant part of this disorder is the lack of desensitization for water and aqua intile injection as allergen even on repeated exposure. Avoidance of allergen as a general principle in any allergic disorder necessitates the evasion of water exposure. Topical application of antihistamines like 1% diphenhydramine before water exposure is reported to reduce the hives. Oil in water emulsion creams, petrolatum as barrier agents for water can be used prior to shower or bath with good control of symptoms. Therapeutic effectiveness of various classes of drugs differs from case to case.

In most patients, the condition lasts only a matter of weeks; in some cases it can last longer (up to six months). The disease resolves completely without long-term effects. Two percent of patients have recurrence.

There is no treatment that will rid the patient of symptoms of aquagenic urticaria. Most treatments are used to lessen the effects of the disease to promote more comfort when the body must come in contact with water.

- Oral antihistamine: Antihistamines such as hydrochloride, hydroxyzine, terfenadine and cyproheptadine have frequently been used to reverse or minimize the effects of aquagenic urticaria. The therapeutic response to these medications will vary from patient to patient and the benefits of applying a histamine antagonist to the skin has not been found to create a direct link to the minimization of water based urticaria effects.

- Topical corticosteroids: Parenteral corticosteroids have been used to help treat aquagenic uricaria in the past. The actual effect of this medication and its benefits are not clear at this time.

- Epinephrine: Patients with severe bouts of urticarial that appear to be acute will frequently use this medication to help decrease the appearance of cutaneous vasodilation. This can also help inhibit mast cell degranulation which may contribute to the presence of aquagenic urticaria.

- PUVA therapy: In one test a 21-year-old woman was given PUVA therapy four times a week in increased doses to help manage the symptoms of aquagenic urticaria. As the dosage was increased the lesions and itching caused by the disease disappeared.

- Ultraviolet radiation: Radiation is commonly used alongside antihistamines to help rid the patient of lesions and outbreaks caused by aquagenic urticaria. This therapy will cause thickening of the epidermis which can prevent water from penetrating this layer and interacting with the cells underneath. Ultraviolet therapy may also cause mast cells to limit their response to stimuli and immunosuppression which can help prevent these reactions.

- Stanazolol: Treatments for the human immunodeficiency virus or HIV have been found to help with the symptoms of aqugenic urticaria as well.

- Capsaicin: This medication is often used for producing Zostrix, a cream applied to lessen pain caused by aquagenic urticaria.

- Barrier methods: In some circumstances an oil in water solution or emulsion cream can be applied to the skin to protect it from water exposure while washing or performing aquatic activities. There does not appear to be a side effect to this method and the application is easier than many other options. Doctors will also recommend that these patients use physical barriers such as an umbrella or protective clothing to avoid contact with water to protect patients from potential outbreaks. Activities such as swimming or visiting a water park will also need to be avoided to minimize the risk of an outbreak.

Southern tick-associated rash illness (STARI) produces a similar rash pattern although it develops more quickly and is smaller. This erythema is also sometimes called erythema migrans or EM. The associated infectious agent has not been determined. Antibiotic treatment resolves the illness quickly.

Erythema (redness) multiforme (EM) is usually a reaction of the skin and mucous membranes that occurs suddenly. It appears as a symmetrical rash and may include the mucous membrane lesions. This means that the body is sensitive to something that causes the skin and mucous membranes to react. The more common mild form is refer to as EM minor. It consists of a skin rash that involve no more than one mucosal surface. The sudden onset will progress rapidly as symmetrical lesions with circular color changes in some or all of the lesions. Rash will spread towards center or trunk of the body. Evenly distributed bumps on the skin become classic iris or target lesions. They have bright red borders and small white bumps in the center.

The cause of EM appears to be a highly sensitive reaction that can be triggered by a variety of causes. The causes can include bacterial, viral or chemical products, such as antibiotics – specifically penicillins or cephalosporins. This reaction is an allergic reaction and is in no way contagious.

Erythema multiforme minus is sometimes divided into papular and vesiulobullous forms.

The cause of erythema toxicum is thought to be an activation of the immune system. Some neonates are more sensitive than others and develop erythematous spots all over the body. Another theory is hypersensitivity to detergents in bedsheets and clothing is sometimes suspected, but the connection remains unproven.

It is thought to be a benign condition that causes no discomfort to the infant. The rash will generally disappear spontaneously in about 2 weeks.

The term morbilliform refers to a rash that looks like measles. The rash consists of macular lesions that are red and usually 2–10 mm in diameter but may be confluent in places.

Patients with measles will have the rash but there are other syndromes and infections that will display the same symptom such as patients with Kawasaki disease, meningococcal petechiae or Waterhouse-Friderichsen syndrome, Dengue, congenital syphilis, rubella, Echovirus 9, drug hypersensitivity reactions (in particular with certain classes of antiretroviral drugs, such as abacavir and nevirapine, and also the antiepileptic drug phenytoin), or other conditions may also have a morbilliform rash.

One cause of morbilliform rash is an allergic reaction to transfused blood/blood components. In such a case, the skin lesions would develop within a few hours (Approx. 4hours) of transfusion along with pruritus. The condition may even present with other symptoms, such as conjunctival oedema, oedema in the lips and tongue, and even localised angioedema. On rare occasions, the condition may even escalate to anaphylactic shock where pulmonary restrictions are seen. The associated cause for this is a reaction against an allergen that is seldom identified during testing. Transfusing products with anti-IgA antibodies to IgA-deficient patients has also been a suspected cause for such reactions. Management usually relates to the stoppage of transfusion for around 30minutes, until given antihistamines take effect. Transfusion may even be continued after, if no further progression is seen.

Treatment is supportive as the infection is frequently self-limiting. Antipyretics (i.e., fever reducers) are commonly used. The rash usually does not itch but can be mildly painful. There is no specific therapy.

Any age may be affected although it is most common in children aged five to fifteen years. By the time adulthood is reached about half the population will have become immune following infection at some time in their past. Outbreaks can arise especially in nursery schools, preschools, and elementary schools. Infection is an occupational risk for school and day-care personnel. There is no vaccine available for human parvovirus B19, though attempts have been made to develop one.

Non-blanching rash (NBR) is a medical term used to describe a skin rash that does not fade when pressed with, and viewed through, a glass.

It is a characteristic of both purpuric and petechial rashes. Individual purpura measure 3–10 mm (0.3–1 cm, - in), whereas petechiae measure less than 3 mm.

A non-blanching rash can be a symptom of bacterial meningitis, but this is not the exclusive cause.

Keratosis pilaris is medically harmless, but many individuals may seek treatment as the condition can cause emotional distress. Topical creams and lotions are currently the most commonly used treatment for keratosis pilaris, specifically those consisting of moisturizing or keratolytic treatments, including urea, lactic acid, glycolic acid, salicylic acid, vitamin D, or topical retinoids such as tretinoin. Corticosteroid creams can also be used as a treatment for KP. Improvement of the skin often takes months and the bumps are likely to return. Limiting time in the shower and using gentle exfoliation to unplug pores can help. Many products are available that apply exfoliation and alpha or beta hydroxy acids.

Some cases of keratosis pilaris have been successfully treated with laser therapy, which involves passing intense bursts of light into targeted areas of the skin. Depending on the body's response to the treatment, multiple sessions over the course of a few months may be necessary.

Lichen aureus (also known as "lichen purpuricus") is a skin condition characterized by the sudden appearance of one or several golden or rust-colored, closely packed macules or lichenoid papules.

Hot tub folliculitis (also known as "Pseudomonas aeruginosa" folliculitis) is a common type of folliculitis, a condition which causes inflammation of hair follicles.

This condition is caused by an infection of hair follicles due to the bacterium "Pseudomonas aeruginosa". The bacterium is commonly found in hot tubs, water slides, and such places. Children are more prone to this because they usually stay in the water longer than adults. Hot tub folliculitis appears on the skin in the form of a rash, roughly resembling chicken pox and then develops further to appear as a pimple. Hot tub folliculitis can be extremely painful and/or itchy, and left alone without scratching will go away much more quickly. If the rash is aggravated, it can stay, worsen, and spread, lasting for months. By that time, it is much more difficult to treat. The dots usually go away after about 7 to 10 days but the condition leaves a hyperpigmented lesion that goes away after a few months.

Normally, the rash does not need specific treatment and will go away on its own. Antibiotics may be prescribed in some cases. If the rash continues to appear longer than the 7- to 10-day time period, a physician should be consulted. Folliculitis that is not treated properly could worsen and cause abscesses.

Allergens that are airborne survive for months or even years by themselves, hence removing anything that can trap and hold the allergens (carpet, rugs, pillows) and cleaning regularly and thoroughly with HEPA filters and electrostatic air purifier systems reduces risk. Frequent hand washing, especially after handling the cat, and washing hands prior to touching eyes, nose, or mouth, and limiting the cat's access to certain rooms, such as the bedroom or other rooms where much time is spent, may also reduce allergic reactions.

Acute cutaneous lupus erythematosus is a cutaneous condition characterized by a bilateral malar rash (also known as a "butterfly rash") and lesions that tend to be transient, and that follow sun exposure.