The skin can turn redder than normal in any region of the body. The redness of skin can be attributed to two main reasons: (1) skin irritation or inflammation, and (2) flushing. Under these conditions, the tiny blood vessels under the skin dilate and allow more blood to pass through. This causes the overlying skin to appear reddish. The reddish tinge of the skin is more apparent in people with lighter skin. However, the reasons and mechanisms for reddish skin is the same in people of both light and dark complexions.
Reasons for Red Neck Skin Rash
Blood vessels can constrict (technically referred to as vasoconstriction) or dilate (technically referred to as vasodilation) depending on the metabolic needs of the tissues that they supply blood to. A red neck usually indicates vasodilation of the underlying blood vessels. The reasons for vasodilation could be physiological or pathological. Physiological triggers for vasodilation include an increase in environmental temperature.
Vasodilation in this situation is a physiological mechanism that helps maintain the normal body temperature. It can also occur due to pathological causes such as inflammation. Vasodilation in this situation is a defense mechanism of the body that is intended to deal with the diseased area. Other skin symptoms such as burning, itching, swelling and rash also accompany vasodilation in such cases.
In some cases, redness of skin may also be caused by the bursting of the underlying blood vessels, leading to an outflow of blood into the tissue spaces. Such a condition is technically referred to as a hematoma. The blood that enters the tissue spaces eventually changes color from dark red to purple or brown. Regardless of the cause, the changes in cutaneous blood flow are more easily visible in people with lighter skin color.
Other signs and symptoms that accompany a red neck rash can provide clues about the underlying cause of the condition.
Read more on burning skin rash.
Causes of Red Neck Rash
A red neck rash can occur due to a variety of causes. The following are some of the common potential causes:
Physiological changes in blood flow: A variety of conditions can cause physiological changes in cutaneous blood flow. For example, cutaneous blood vessels dilate in order to dissipate heat when the outside environment is hot.
Consumption of alcohol, spicy foods, and caffeinated beverages also cause dilation of the cutaneous blood vessels. Hormonal changes such as those occurring during pregnancy and menopause can also cause blood vessel dilation. And so can strong emotions such as anger.
An allergic skin reaction is a common cause of red neck rash. An allergic reaction is elicited in some individuals after contact with an otherwise harmless substance. The immune system launches an immune attack against the harmless substance, mistaking it to be a pathogen. Allergic reactions can either be localized or systemic. A localized skin reaction to an allergen is termed as allergic contact dermatitis. Some of the possible allergens that can cause allergic contact dermatitis on the neck include skin creams, textiles, and metal components in the jewelry that is worn around the neck.
Infections of the skin caused by a variety of bacteria, fungi and viruses are also common reasons for red neck rash. An example of a bacterial infection that affects the skin on the neck is impetigo. Infection of hair follicles in the skin can cause folliculitis. If the infection spreads to deeper subcutaneous layers, then a serious condition known as cellulitis can occur.
Examples of viral infections affecting the skin on the neck include chickenpox, shingles, and infection with herpes simplex virus. Fungal infections can affect skin in any part of the body. Fungal infections of the skin on the neck are usually continuous with the fungal infections of the beard (technically referred to as tinea barbae) and the fungal infections of the scalp (technically referred to as tinea capitis).
A number of substances can cause skin irritation and inflammation upon contact. Such a skin reaction is termed as irritant contact dermatitis. It should be noted that irritant contact dermatitis is not the same as allergic contact dermatitis. No allergic reaction occurs in irritant contact dermatitis.
Some of the substances that can cause irritant contact dermatitis include soaps, detergents, chlorine in water and some skin cosmetics. Constant rubbing of the skin by the clothing that covers the neck may also irritate the skin. In addition, harmless substances like sweat and water can also cause skin irritation if they are in contact with the skin for long periods.
Read more on irritant contact dermatitis.
Rosacea is a chronic skin condition that is characterized by extreme redness of the skin. The affected skin areas often contain blisters that are filled with pus. Rosacea mostly affects women who have a light skin complexion. The face is the most commonly affected area. The exact cause of rosacea is not known. However, factors like spicy foods, alcohol, sunlight, hot weather, and stress are thought to either trigger the condition or worsen a pre-existing condition.
Atopic dermatitis is a skin condition that is characterized by a red, dry and itchy skin. This condition mostly affects the skin in the body folds. For example, atopic dermatitis commonly affects the skin in the elbow, knee, ear and neck regions. Also known as eczema, atopic dermatitis tends to accompany other conditions like allergic rhinitis (also known as hay fever) and asthma. Eczema often starts in childhood.
Acne vulgaris is a skin condition that is characterized by reddish skin and pimples. This condition is a result of blocked hair follicles that become infected. The skin on the face, shoulders, scalp and chest are the most commonly affected areas. The skin on the neck may also be affected. Acne vulgaris is a common condition during the teenage years.
Heat rash occurs when the sweat gets trapped within the sweat ducts that lie under the skin. This causes the appearance of fine skin bumps and a red rash that is referred to as heat rash. Also known as prickly heat or miliaria, heat rash is common among infants and young children. However, adults can also get affected.
Psoriasis is an autoimmune disorder that causes chronic inflammation and thickening of the skin. There are multiple types of psoriasis. The most common form is known as psoriasis vulgaris. The skin lesions in psoriasis are in the form of plaques that are red or silvery white.
Seborrheic dermatitis is an inflammatory skin condition that is characterized by excessive sebum production and a crusty, scaly, yellowish skin. The skin on the face and the scalp are the most commonly affected areas. The exact cause of seborrheic dermatitis is not known.
Images sourced from Dermatology Atlas.