Skin rash is a common symptom in children and adults, but it is definitely more common in children. Chickenpox and erythema infectiosum are common in children, and patients with these infections have a characteristic skin rash, but after a certain age, they are not the leading cause. Rash in adults can be a benign condition, not always associated with infections. But sometimes it can point out to a worrying disease such as leukemia.
If you have a rash as an adult, is there any way to know whether or not to worry? What causes skin rash in adults? What signs and symptoms should alert you to ask your doctor right away and find out the cause of your rash? We will cover all of these topics in the following paragraphs.
Types of skin rash in adults
The types of skin rash in adults are the same as in children. But while children’s skin rashes are mostly infectious, the most common causes of rash in adults are either allergic, inflammatory or hemorrhagic. Each subtype has distinct pathophysiology, as you will see next:
Inflammatory skin rash
As the name implies, this type of skin rash appears as a result of inflammation in the skin or the underlying tissues. It usually shares the same signs of inflammation we are used to seeing: heat, redness, and tenderness. In inflammatory skin rash, the affected area becomes reddened, and it’s a bit more warm to the touch. It is usually tender, but this feature depends on the severity and the extension of the rash. Inflammatory skin rash appears due to certain substances released by your white blood cells, and may or may not be associated with infectious diseases.
Allergic skin rash
In some cases, the immune system has an exaggerated response to certain particles or substances in our environment. This immune problem is founded on hypersensitivity that triggers inflammatory reactions, and it is called allergy. It shares some features with inflammatory rash, but in the majority of cases, it is dispersed in various areas of the body. These causes are only worrying in adults when accompanied by certain signs and symptoms.
Hemorrhagic manifestations
There’s another type of rash that is not associated with the immune system. Instead, it is caused by delayed clotting and repair of tissues. The body continuously undergoes microscopic injuries, and clotting contributes to healing them before the blood starts leaking to the interstitial tissue. Hemorrhagic skin rash appears when blood clotting is not fast enough. We will often see red spots or red areas in the skin, and they are sometimes associated with a traumatic event. When not associated with trauma, hemorrhagic manifestations in adults are by far the more worrying type of rash.
Infectious skin rash
Both children and adults can become infected with systemic diseases like chickenpox, measles, and others. They are not common in adults, and they are usually more severe and worrying as we grow older. Other infectious causes include ringworm and other infections of the skin. Each one of them displays characteristics we have discussed above, and the severity of the condition depends on the cause.
As you can probably guess by reading this short list, some types of rash in adults are not to be classified in one single type. You can have an infectious and inflammatory rash or an allergic skin rash with infectious symptoms due to itching and scratching. Thus, after determining the type of skin rash, we should also think about the probable cause.
What causes a rash and when to start worrying about them
Herpes virus
There are many types of herpes virus, and some of them are transmitted through sexual intercourse. They are more common in adults and give out a characteristic rash with vesicles that break down, releasing a highly contagious liquid and leaving open sores that itch and burn. In the majority of cases, this infection is not a cause of worry, unless the patient is severely immunocompromised (as in HIV patients), or in case the extension of the rash starts covering an extensive area of your body.
Scabies
It is another infection, this time caused by a parasite instead of a virus. These microorganisms create deep crypts in the skin where they hatch their eggs, and the infection keeps spreading further unless treated with the appropriate medication. Scabies rash causes severe itching, which becomes more intense at night, and it is highly contagious. It is an annoying condition, but not a life-threatening one.
Psoriasis
It is due to a dysfunction of the immune system, which becomes activated after episodes of stress and certain infections. The skin rash in psoriasis is an inflammatory rash, but it also leaves flakes or scales in the skin and itchy red areas that usually appear in the scalp and other areas of the body. It is not a life-threatening condition, and it is usually treated with topical medications.
Contact dermatitis
It is the most common type of allergic skin rash, and it appears when the skin is in contact with certain substances or triggers of inflammation. Contact dermatitis is not a life-threatening cause of rash, but other forms of allergic rash may become a concerning cause, especially when they are triggered by food allergies.
Folliculitis
It is the infection of the hair follicles, usually by opportunistic bacteria that live in the skin and under certain conditions might infect and colonize this area. Folliculitis is not a life-threatening condition.
Blood cell alterations
Alterations of blood values may be a cause of a rash in adults, especially when there is a dysfunction or low levels of thrombocytes. These cells are capable of triggering blood clotting, and causes in adults include infectious diseases like chickenpox, and severe blood alterations, as in leukemia. They trigger a hemorrhagic type of skin rash. Infectious diseases like chickenpox are more severe in adults. Moreover, they have a higher risk of suffering from myeloproliferative diseases like leukemia. Thus, they should be investigated thoroughly as soon as hemorrhagic rash is suspected.
Leukemia as a cause of skin rash
The most feared cause of skin rash in adults is leukemia, a type of blood cancer. However, it is by far one of the most uncommon causes. The majority of adults with a skin rash will be diagnosed either with infectious diseases or allergic reactions. But in some cases, it might be due to hemorrhagic causes, and leukemia should be ruled out sometimes.
Leukemia causes a skin rash because it is a dysfunction of the cells in the bone marrow. These cells produce red blood cells, white blood cells, and thrombocytes. By increasing the production of white blood cells exaggeratedly, leukemia impairs the production of other cell lines. Thus, the majority of patients have low levels of thrombocytes, and their blood clotting function becomes impaired.
However, as stated above, leukemia is not the most frequent cause of skin rash. This type of skin cancer is usually diagnosed through a combination of signs and symptoms, and not by having skin rash alone. Thus, let us review what signs and symptoms usually accompany skin rash in cases of leukemia and other life-threatening conditions in adults.
Alarming signs and symptoms
We should be alarmed about a skin rash and look for medical assistance in two different scenarios:
- After noticing certain characteristics of the rash
- After noticing a combination of signs and symptoms
Alarming signs related to the skin rash include the following:
1) Large extension of the rash
If the rash covers a large extension of your body or your body as a whole, it is a good idea to ask for medical help. Infectious diseases causing this type of rash are more severe as we grow older, and it might be due to a hemorrhagic cause.
2) Rapid or sudden spread of the rash
If the rash spreads in hours or minutes, it is very likely an allergic cause. Some types of allergic rash are very dangerous, especially when accompanied by symptoms we will discuss below.
3) An oozing rash
In many cases, itching and scratching cause infection of a rash, and what was not originally a severe cause becomes complicated with infection.
Alarming signs and symptom that may accompany serious causes of rash include:
1) Fever
The combination of skin rash and fever might not be distressing in children, but it should raise an alarm in adults. It may be due to infectious causes that complicate into hemorrhagic conditions, and in some cases, leukemia should be ruled out as well.
2) Bleeding episodes
If you have a skin rash with bleeding gums or find blood in your stools or your urine, it is a good idea to talk to your doctor right away. Your rash is very likely caused by skin hemorrhage, and it is important to find out why.
3) Breathing difficulty
A skin rash that spreads rapidly accompanied by breathing difficulties should be treated as an absolute emergency, especially in allergic individuals. Food allergies are the most common cause.
References
American Osteopathic Association. (2015, October 5). Adult rashes with fever call for emergency treatment, can signal life-threatening illness: Survival rates improve with aggressive, early treatment for these difficult to diagnose conditions. ScienceDaily.
Hiddemann, W. (2016). Handbook of acute leukemia. Springer International Publishing.