The skin is the largest sensory organ in our body. A variety of receptors reside inside skin that covers the surface of an average adult human body. The process of sensing the external environment begins when the receptors in the skin get stimulated upon contact with an external agent.
Signals from these sensory receptors are then relayed to the central nervous system, where sensory perceptions of the external agent are generated, and appropriate actions are planned. These sensations could be pleasant (like warmth and softness) or unpleasant (such as hot and cold, pain, and pressure). The unpleasant pain sensations are warning signs that allow us to respond by either eliminating the responsible agent, or by moving away from it. Sometimes, sensations are created even in the absence of any external stimuli.
Reason for Burning Sensation
A burning sensation is usually a result of inflammation. Inflammation happens in response to tissue injury. It is a short-lived response by the body aimed at limiting the tissue damage due to an injury. Inflammation is characterized by four physiological responses at the site of the injury: pain, swelling, heat and redness.
These physiological responses are produced by the secretion of chemicals known as the pro-inflammatory cytokines. These cytokines dilate the blood vessels in the injured area, resulting in exodus of fluid and immune cells from the blood vessels into the tissue. These cytokines also stimulate the pain receptors (technically known as nociceptors) in the vicinity, which are responsible for the burning sensation that characterizes the site of inflammation.
Thermoreceptors in the skin also get stimulated, causing the sensation of warmth in the area of inflammation. Sometimes, the burning sensation in the skin might occur even without any apparent injury.
Read more on itchy skin.
Causes of Burning Skin Sensation
A burning skin sensation can be caused in a variety of conditions. Some of these are:
A common cause of burning skin sensation is trauma to the skin. The trauma can be due to physical or chemical agents. Trauma to the skin could happen due to blunt force impact in any violent event. Injuries due to sharp objects will also cause injury and inflammation. Skin burns can happen due to heat or strong sunlight (sunburns). Burning skin sensation could also be a result of exposure to ice, and frostbite. Certain chemicals also cause skin burns when they come in contact with the skin. Insect bites and stings are also frequently associated with inflammation and a burning sensation at the site of the bite.
Skin allergies also cause pain and burning sensations. An allergic reaction is caused when the skin comes in contact with an allergen. An allergen is usually a harmless substance that does not cause any adverse skin reaction in most people. However, in some individuals, an immune response is generated whenever the allergen comes in contact with the skin.
Itching and rashes may accompany the burning sensation at the site of skin contact. Latex is an example of a common allergen that can cause an allergic skin reaction upon contact. In some cases, an allergic reaction may occur even without actual physical contact with an allergen. Atopic dermatitis is an example of such a condition.
Chemical substances present in certain plants can cause inflammation and burning sensation when they come in contact with the skin. Poison ivy and stinging nettles are two examples of such plants. Physical contact with these plants produces a local inflammatory reaction on the skin, which is characterized by itching and other symptoms of inflammation. Capsicain, extracted from chilli peppers, causes burning sensation and pain when applied to the skin in a concentrated form. It is used in a dilute form in certain skin creams. Concentrated mustard oil is another common substance that causes burning sensation when applied to the skin.
A burning sensation is also a feature of many skin diseases. Examples include contact dermatitis, eczema or atopic dermatitis, psoriasis, and urticaria. The primary symptom of these skin diseases is an itchy skin. Vigorous scratching caused by the itching sensation results in skin damage. It is this skin damage that is responsible for the burning sensation. Therefore, the burning skin sensation in skin diseases is usually a secondary manifestation rather than a primary presentation. Moreover, skin damage due to scratching may also lead to infections, which in turn cause inflammatory reactions.
Cutaneous decompression sickness
Decompression sickness (or bends) refers to a constellation of symptoms such as pain in muscles and joints, cramps, numbness, burning sensation, nausea, and paralysis, caused by nitrogen bubbles forming in the tissues. This happens in divers who depressurize too quickly by ascending rapidly through the water. The gas bubbles also deposit in the capillaries of the skin. This may be a potential cause of burning skin sensation in divers.
Drugs and toxins
Burning sensation in the skin can be caused by many drugs and toxins. This burning sensation may or may not be accompanied by any other symptom. The technical term used for skin rashes and other symptoms that arise from using certain pharmaceutical drugs is dermatitis medicamentosa. The symptoms are commonly referred to as drug eruptions.
Apart from medicines, injecting illicit drugs may also cause a burning skin sensation (among other symptoms) due to injury to the nerves at the injection site. Many toxins are also capable of causing burning skin sensation. These toxins encompass both natural and synthetic compounds. A common toxin that causes burning skin sensation is arsenic. It is noteworthy that arsenic is a widely used toxin for intentional poisoning.
Peripheral neuropathy refers to nerve disorders caused by damage or irritation to the nerves outside of the central nervous system (brain and spinal cord). Peripheral neuropathy can result from infections, trauma, and toxins. Hereditary and metabolic factors could also be contributory factors. Pinched nerve and diabetic neuropathy are two examples of peripheral neuropathy.
Pinched nerve is caused by a compression of the nerve root as it emerges from the spinal cord. Diabetic neuropathy is caused by damage to the peripheral nerves due to long-term diabetes. The burning sensation caused by peripheral neuropathy is also accompanied by tingling, prickling, numbness, and even muscle weakness and paralysis.