A blister is a defense mechanism of our body. It is an area of the skin wherein the outer layer (epidermis) separates from the next layer (dermis). A clear liquid called serum collects within this gap while the epidermis re-grows from beneath. Serum is the component of blood that remains after clotting agents and red blood cells have been removed. It seeps out from the surrounding tissues as a reaction to trauma. The serum serves as a cushion that protects the tissue underneath, guarding it against further damage until it heals. Other bodily fluids may also form within the bubble, such as pus if it becomes infected. Blood may also form within if the blister is a result of sub-dermal bleeding. This is when a tiny blood vessel near the surface of the skin ruptures and blood seeps into a tear between the skinís layers. This usually happens when the skin is pinched, crushed or squeezed very tightly.
Blisters form as a result of trauma on the skin. For instance, blisters on the feet may arise because of too much pressure from tight shoes. Blisters on hands may form if an area of the skin is rubbed intensely, such as when a person does not wear protective gear while doing strenuous activities like biking. Blisters may also form due to certain medical conditions such as chicken pox, herpes, and pemphigus.
Smaller blisters are known as vesicles. On the other hand, larger blisters that are typically more than half an inch are known as bullae.
There are many causes of blisters. These include:
Blisters can be caused by physical and chemical irritation, as well as extreme heat or cold. Physical irritation may result from friction, such as when the skin is rubbed too intensely. For example, foot blisters may develop due to wearing tight and uncomfortable footwear. Blisters may also form as a reaction of the skin to a chemical irritant. An example of a chemical irritant is a chemical weapon known as a vesicant, which has the ability to cause large blisters on the bodies of those come in contact with it. Blisters may also arise due to burns, even sunburn. Frostbite may also trigger blisters, which start to develop when the skin is re-warmed.
Allergic contact dermatitis, which is a form of eczema, may bring about the formation of blisters. This is caused by an allergic reaction to a chemical, such as poison ivy, detergents, and solvents. Blisters can also develop due to allergies to insect bites and stings.
Some medications like furosemide and nalidixic acid can cause mild blisters. Others, like doxycycline, increase the sensitivity of the skin to sunlight, thus increasing the risk of having blisters from sunburn. In more severe cases, medications can trigger serious blistering disorders like erythema multiforme and toxic epidermal necrolysis (TEN), which causes harsh skin damage to at least 30 percent of the surface of the body.
- Skin conditions
Some autoimmune diseases have blisters as a symptom. An example is pemphigus, wherein blisters form if pressure is applied to an area of the skin. The blisters easily burst and this increases the chance of infection. Other diseases include bullous pemphigoid, which causes large blisters to form typically in people over the age of 60, and dermatitis herpetiformis, which is a disease wherein same-sized and shaped itchy blisters form on the back, elbows, knees, and buttocks.
Examples of infections that result in blistering are chicken pox and shingles (caused by the virus varicella zoster), bullous impetigo (caused by the bacteria called staphylococci), herpes types 1 and 2, and coxsackievirus infections.
Blisters usually manifest as a swelling on the skinís surface that contains fluid. Some blisters may be painless, while some may be sensitive to pressure and cause discomfort. Blisters may form singly or in clusters, depending on what caused them to develop.
Blood blisters are colored dark and are normally more painful than other blisters. Infected blisters contain yellow or green pus. Like blood blisters, they are painful to the touch. The skin surrounding an infected blister may appear red or there may be thin red streaks. It may also feel warm.
In most cases, the fluid within the bubble is slow reabsorbed by the body as new skin grows under it. The skin on top then dries and sheds off. This whole process takes around three to seven days on the average.
If you consult a doctor regarding your blister(s), he/she will ask you regarding your family and medical history, current illnesses and medications youíre taking for those, and if you have been exposed to allergens and chemicals.
The doctor will make his/her diagnosis depending on your history and on the appearance of your blisters. If an allergic reaction is suspected, the doctor may recommend you to undergo patch tests to identify the allergens responsible for it. In worse cases, the doctor may conduct a skin biopsy wherein a small patch of tissue is removed and sent to a laboratory for further examination.
Blisters are usually caused by physical and chemical irritation. However, blisters that form without any apparent causes may be a sign of a medical condition. If this is so, the doctor may advise you to undergo more tests to trace the cause of blistering.
There is no way that you may prevent blistering when you have a medical condition, such as a skin or autoimmune disease. However, blisters arising from skin irritation may be easily prevented. As much as possible, minimize friction. If possible, apply talcum powder or petroleum jelly on blister-prone areas in order to reduce friction. Wear the appropriate socks, footwear, and other protective gear if needed. Blisters are more likely to develop on moist and warm areas, so make sure that you keep your hands and feet dry. Avoid exposure to chemical irritants that may trigger eczema, which can then bring about blistering. Stay away from and remove possible sources of allergens such as curtains and plants.