Allergy

This condition can cause blotches to appear on the skin after wearing clothing items, eating foods or using medications that trigger an allergic reaction. In some cases these blotches will appear if a person has sensitivity to alcohol.

Weather Condition

Very cold and dry weather can cause blotches on the skin, particularly on the face as it is often exposed to these elements and loses moisture very quickly. Some have noted that blotches appear on their face in cold temperatures after stepping out of a warm shower or bath.

Unhygienic Conditions

Wearing dirty clothes or failing to wash after strenuous activity can cause the skin to develop blotches. Those that do not develop a consistent hygienic routine will constantly expose their body to viruses or bacteria that will not be washed away which may lead to blotches on the skin or a rash.

Sun Damage

If the skin is exposed to high amounts of ultraviolet rays from the sun it can cause the skin to turn blotchy, red, tenderness or develop pain.

Purpura

A reddish purple blotch on the skin is often caused when small blood vessels become weak and begin to leak. This can be a symptom of many conditions such as congenital rubella syndrome, meiningococcema, taking drugs that affect the function of platelets in the blood stream, vasculitis and others.

Rosacea

Blotches that are prominent on the cheeks, nose or forehead may be caused by rosacea. This may also cause pus-filled bumps to appear beneath the skin. While the final cause of this condition is unknown, it is believed that stress, consuming spicy foods, excessive sun exposure, drinking alcohol, taking hot baths or using medications that affect blood vessel function may play a role in the development of this disease.

Acne

Red or brown blotches that are flat may be macules, the scars left behind as a blemish heals. Sun exposure can make these marks worse, but in general they should fade away with time.

Birthmarks

Hemangioma or birthmarks are a blotch on the skin with excessive pigmentation that become visible after a child is born, though in some cases they may develop years later. In this case the mark is generally permanent and will develop in early childhood.

Petechiae

Actions such as strenuous coughing or trauma to the area can cause the capillaries to bleed and leak into the mucus membranes below the skin. This may lead to small red or purple spots or blotches appearing in the affected area. These blotches are the most common on the legs, though they will spread to other areas of the body.

Dermatofibromas

This condition is caused as fibroblasts or soft tissue begins to accumulate on the skin, leading to a firm, small red or brown bump to appear. These are most common on the torso or legs. A physician should inspect these, particularly if they are accompanied by pain or itching.

Pyogenic Granulomas

This condition is caused by an overgrowth of the body’s capillaries, causing a red, blue, brown or purple blotch to appear on the surface of the skin. It is unknown why this condition appears, but it is not cancerous and not the result of a genetic condition. In some cases these blotches will appear after trauma that damages nearby blood vessels. Pyogenic granulomas are more common in children.

Cherry Angioma

This condition causes large blotches on the skin that will change from red to blue as they enlarger. This condition can appear on any part of the body, though it is not known what specifically causes it to appear. This condition also tends to run in families.

Hives

Hives can vary greatly in their appearance, causing blotches that are a few millimeters or a few inches in size. These are elevated, smooth bumps on the skin that can alter their position and size rapidly. The tendency to develop hives tends to run in families, though items such as insect stings or allergies can cause them to appear.

Diaper Rash

Blotches on the skin that are found in the area where a diaper is placed on a child can be a simple case of diaper rash. Exposure to antibiotics, moisture collected by the diaper, allergies, diet, infections and more can cause these blotches to appear. These blotches may also sting, causing discomfort when the diaper is changed.

Measles

Measles will begin as a gray spot inside the mouth, but red blotches will appear on the skin a few days later. This condition may also cause watery eyes, fatigue, fever or sore throat. Measles is a viral infection that can spread very quickly, with symptoms appearing around a week after the initial infection.

Insect Bites

Mosquitos and other insects like lice, bed bugs, mites or ants can cause red blotches to appear on the skin after you have been bitten. This may also cause an allergic reaction on the skin that can be painful or itchy.