| Blister | |
|---|---|
 | |
| Blisters from abrasive rubbing are common on the feet. | |
| Specialty | Dermatology |
| Causes | Heat,cold,electricity,chemicals,friction,radiation |
Ablister is a small pocket ofbody fluid (lymph,serum,plasma,blood, orpus) within theupper layers of the skin, usually caused by forceful rubbing (friction), burning, freezing, chemical exposure or infection. Most blisters are filled with a clear fluid, eitherserum orplasma.[1] However, blisters can be filled with blood (known as "blood blisters") or with pus (for instance, if they become infected).
Smaller blisters are calledblebs. The word "blister" entered English in the 14th century. It came from theMiddle Dutchbluyster and was a modification of theOld Frenchblostre, which meant a leprous nodule—a rise in the skin due toleprosy.
Indermatology, the wordsvesicle andbulla refer to blisters of smaller or greater size, respectively.[2]
Some sources recommend not to pop a blister. If popped,bacteria can enter. Excess skin should not necessarily be removed as the top layer protects the soft tissue underneath.[3]
A blister may form when the skin has been damaged byfriction or rubbing, heat, cold or chemical exposure. Fluid collects between the upper layers ofskin (theepidermis) and the layers below (thedermis). This fluid cushions the tissue underneath, protecting it from further damage and allowing it to heal.
Intense rubbing can cause a blister, as can any friction on the skin if continued long enough. This kind of blister is most common after walking long distances or by wearing old or poorly fitting shoes.[4][5][6] Blisters are most common on the hands and feet, as these extremities are susceptible while walking, running, or performing repetitive motions, such as joystick manipulation whilst playing certain video games, certain sports (e.g., baseball pitching), digging with a shovel, playing guitar or bass, etc. Blisters form more easily on damp skin than on dry or soaked skin,[7] and are more common in warm conditions. Less-aggressive rubbing over long periods of time may causecalluses to form rather than a blister. Both blisters and calluses can lead to more serious complications, such as footulceration and infection, particularly when sensation or circulation is impaired, as in the case ofdiabetes,neuropathy orperipheral artery disease (PAD).
This type of blistering is one of the tools used to determine thedegree of burns sustained. First and second degreeburns may result in blistered skin; however, it is characteristic of second degree burns to blister immediately, whereas first degree burns can have blisters after a couple of days.Sunburn can also result in blisters.
Blisters can also form on the hands and feet as a result of tissue damage incurred byfrostbite.[8]
Sometimes, the skin will blister when it comes into contact with a cosmetic, detergent, solvent, or other chemical such asnickel sulfate,Balsam of Peru,[9] orurushiol (poison ivy,poison oak,poison sumac).[10] This is known ascontact dermatitis. Blisters can also develop as a result of an allergic reaction to an insect bite or sting. Somechemical warfare agents, known asblister agents or vesicants, cause large, painful blisters wherever they contact skin; an example ismustard gas.
Ablood blister usually forms when a minuteblood vessel close tothe surface of the skin ruptures (breaks), and blood leaks into a tear between the layers of skin. This can happen if the skin is crushed, pinched or aggressively squeezed.
There are also a number of medical conditions that cause blisters. The most common arechickenpox,herpes,impetigo, and a form ofeczema calleddyshidrosis. Other, much rarer conditions that cause blisters include:
Friction blisters are caused by excessshear stress between the bottom and surface of the skin and the body. The strata of skin around thestratum spinosum are most susceptible to shear. As the stratum spinosum tears away from the connecting tissues below, plasma from the cells diffuses out. This plasma solution helps new cells divide and grow into new connective tissues and epidermal layers.
The clear fluid will be reabsorbed as new cells develop and the swollen appearance will subside. Painful blisters located on hands (palmar surface) and feet (plantar surface) are due to tissue shearing deeper in the epidermis, near nerve endings. Lower tissues are more susceptible to infection.
Friction blisters, caused by rubbing against the skin, can be prevented by reducing the friction to a level where blisters will not form.[4][5][6][12] This can be accomplished in a variety of ways.
Blisters on the feet can be prevented by wearing comfortable, well-fittingshoes and clean socks. Inherently ill-fitting or stiffer shoes, such as high heels and dress shoes, present a larger risk of blistering. Blisters are more likely to develop on skin that is moist, so socks that manage moisture or frequent sock changes will aid those with particularly sweaty feet. While exercising or playing sports, special sports socks can help keep feet drier and reduce the chance of blisters.[13] Before going for a long walk, it is also important to ensure that shoes or hiking boots have been properly broken in.
Even before a "hot" or irritated area on the foot is felt, taping a protective layer of padding or a friction-reducing interface between the affected area and the footwear can prevent the formation of a blister.[14] Bandages,moleskin and tapes generally must be applied to the foot daily, and most have a very highcoefficient of friction (COF), but a friction-management patch applied to the shoe will remain in place much longer, throughout many changes of socks and insoles. This type of intervention may be used with footwear that is worn daily, with specialty shoes and boots like hockey skates, ice skates, inline skates, ski boots and cleats, or even with orthotic braces and splints. For periods of sustained use such as hiking and trail running, especially where water ingress or moisture build up in the shoe or boot can occur, moisture wickingliner socks can provide the required friction protection.
To avoid friction blisters on the hands, gloves should be worn when using tools such as a shovel or pickaxe, doing manual work such as gardening, or using sports equipment like golf clubs or baseball bats. Oars used for competitive rowing are known for causing frequent blisters on the hands of oarsmen. Weightlifters are also prone to blisters as are gymnasts from the friction developed by the rubbing against the bars. To further reduce the occurrence one can tape the hands, and there are also a number of products on the market that claim to reduce the occurrence of blisters. These are all intended to be worn as a liner underneath a glove. The majority of these offerings simply add padding, and create a layer that reduces the coefficient of friction between the skin and the glove.
Alubricant, typicallytalcum powder, can be used to reduce friction between skin and apparel in the short term. People put talcum powder inside gloves or shoes for this purpose, although this type of lubricant can actually increase the friction in the long term as it absorbs moisture. Increased friction makes blisters more likely.
Sunscreen and protective clothing should also be used during the hottest part of the day to avoid blisters from sunburn. Avoiding sunlight during midday is the best way to avoid blisters from sunburn. Protective gloves should be worn when handling detergents, cleaning products, solvents and other chemicals.
