Main symptoms and types of hives

Main symptoms of hives​

When hives develop, raised, reddish wheals (wheals) appear on the skin, accompanied by a burning sensation and itchiness. However, it's possible that other conditions with similar symptoms are not hives, so it's important to understand the characteristics of hives to make a proper diagnosis.

When making a diagnosis, the timing of the onset and the duration of the itching are important factors. Common triggers include after meals, after contact with chemicals or medications, and after exposure to sudden temperature changes such as extreme heat or cold. Furthermore, stress and fatigue can trigger hives, and the itching itself can be a source of stress. It is also believed that hives often develop at night as the body warms up before going to sleep.

Hives caused by food allergies typically develop within 30 minutes to an hour of eating the food. Check if you ate anything you hadn't eaten before within 30 minutes of the hives appearing. In cases of heat urticaria and cold urticaria, symptoms may appear after a bath or after exposure to cold wind in winter.

One characteristic of hives that appear on the skin is that the symptoms usually subside within 24 hours and do not persist for long. According to research up to 2008, only a small number of people (0.5-1%) of the total population have chronic hives that last for more than 6 weeks. Therefore, if symptoms persist for several days, you should consider the possibility of something other than hives. When you go to the hospital for a consultation, you will be asked questions such as "when did it start?", "where did it appear?", "what did it feel like?", "when did it appear?", and "how severe were the hives?", so it is helpful to take pictures with your smartphone or make notes when the symptoms appear.

If the cause cannot be identified, itching is treated with antihistamines or other medications for idiopathic urticaria. In addition, there are cases where symptoms are similar to urticaria but are not urticaria, such as insect bites from mites or centipedes, erythema multiforme caused by infections such as herpesvirus or mycoplasma, and shiitake dermatitis caused by undercooked shiitake mushrooms.

If you have raised rashes and itching, but your skin doesn't turn red, it's likely angioedema, which occurs closer to the body than the surface. Angioedema can occur anywhere in the body, including mucous membranes such as the mouth and throat. It's a condition often triggered by stress or certain medications, and while it may take several days to heal compared to hives, it does heal without leaving scars.

To alleviate the itching, one possible approach might be to first try using a topical medication that is known to be effective for hives and has few side effects.

About hives in babies and children​

There are differences in the characteristics of hives between children and adults. It's common for people to experience hives at some point, with about 1 in 4 or 5 people experiencing them at least once in their lifetime. Acute hives and chronic hives account for the majority of cases. Acute hives are more common in children, while chronic hives are more common in adults. The causes also differ; in children, they are often caused by infections such as upper respiratory tract infections or food allergens, while in adults, they are often due to stress or environmental factors. Furthermore, mechanical urticaria, delayed-pressure urticaria, and aspirin-induced urticaria are less common in children but more common in adults.

In children, hives caused by food allergies are common, and in addition to rashes, symptoms such as a scratchy throat, itchy eyes, and in severe cases, vomiting, diarrhea, and difficulty breathing may occur. If symptoms other than skin symptoms are present, it is a severe systemic allergic reaction called anaphylaxis, and immediate treatment is necessary. The most common food allergen for children aged 0-6 is chicken eggs, while shellfish become more common for children aged 7 and older.

Furthermore, many children come to the clinic mistaking erythema infectiosum, also known as fifth disease, for urticaria (hives). Because it presents as a pale red rash resembling a lace curtain and is accompanied by itchiness, they tend to mistake it for urticaria.

​Areas where hives are likely to occur

Urticaria (hives) tends to appear on areas with soft skin, such as the thighs, abdomen, buttocks, behind the knees, cheeks, and neck. However, it can also occur on the soles of the feet, the backs of the hands, and the scalp. Urticaria can occur anywhere in the body. Rarely, it can occur in the mouth, throat, or airways, and symptoms such as shortness of breath and hoarseness may appear along with itching.

Furthermore, scratching or rubbing hives can release more allergens such as histamine and leukotrienes into the bloodstream, creating a vicious cycle where touching the affected area makes it progressively redder and itchier. Since raised welts may remain for some time, try to avoid irritating the affected area as much as possible.

Source: "The True Common Sense of Hives" by Kunihiro Kiyomasu (Medical Economics Co., Ltd.)