Hives, or urticaria, is a type of an allergic reaction in the form of a rash that consists of swollen, red, itchy welts. They can vary in size and severity, from small, fairly unnoticeable welts, to the most severe patches that tend to hurt and itch a lot.

Hives are caused by a variety of factors such as food, scratching, infections, medications, alcohol, and emotional stress. All of these can cause an outbreak of hives and even worsen the condition if there is a prolonged exposure to the triggers. It has been estimated that about 20 percent of the world population has experienced hives at some point in their lives. But, the burning question of today is, how long do hives actually last?

Acute Hives

It has been reported numerous times that hives, as pesky and annoying and sometimes scary, they are, are not a serious or contagious condition. However, prolonged urticaria can definitely make a person’s life more difficult as the welts tend to itch a lot and sometimes even cause pain or a stinging sensation of the affected area. Often, the patched move around the body, causing an unpleasant feeling.

Typically, hives last only a few hours and do not leave any changes to the skin. In most cases, the outburst of hives may last only for a few minutes when one is exposed to a trigger, however, sometimes they can last several hours. This is usually the case with physically induced urticaria. Many a time a person would not even realize that they have hives as the condition can develop overnight, while the person is asleep and go away by the time the morning comes.

Other times, when exposed to a trigger that causes hives, an individual may develop an itchy rash that will last for several hours, and go away just as painlessly as the type that lasts for a few minutes. Sometimes, this type of hives will be treated with a simple over-the-counter antihistamine medication or a cold patch that helps reduce the itching and swelling.

There are, of course, cases when hives last up to one day. Most hives do last up to 36 hours and are easily treatable with antihistamines and other home remedies. Usually, this type of hives is caused by food or drug reactions.

Chronic Hives and Angioedema

Chronic hives and angioedema are usually diagnosed when swelling and hive last for more that six weeks. The cause of chronic hives is not easily detectable even after a detailed testing, thus this condition is called chronic idiopathic (unknown) urticaria. Usually, around 50 percent of these cases are linked to some immune findings, thyroid disease or other hormonal issues, and in rare cases, even cancer.

Physical Urticaria

Physical urticaria develops due to the physical causes. The most common reason for these long-lasting hives is dermographism. These hives occur within minutes of scratching the skin, and most often the rash is linear and follows the path of the scratch. In most cases, the swelling and itching will go away after 15 to 30 minutes, but in some extreme cases, it can last for a few hours, even days!

Delayed pressure urticaria is a swelling that occurs in the areas of the skin that are under constant pressure from sock’s bands or belts. It can also occur on the thighs after long periods of walking, especially applicable to women who wear dresses and skirts in the summer, as well as on the buttock area after sitting for a few hours. This type of urticaria should go away after about 30 minutes after the removal of a trigger.

Cold urticaria is a type of urticaria caused by the exposure to low temperatures followed by re-warming. This type can be somewhat life threatening because of the fact that in these cases the body cools down rapidly, for example by plunging into a cold swimming pool. However, in most cases, when the body reaches its natural temperature, the cold hives will go away.

Solar urticaria is a fairly rare condition in which a person sensitive to ultraviolet or UV radiation develops hives that can outbreak on visible and even covered areas of the skin. At times, one can develop sun-induced hives even when exposed to visible light that does not come directly from the sun. The rash may last anywhere from a few minutes to 24 hours.

 Even though most cases of hives last fairly short, you should definitely be wary of the signs

When to call 911?

You should call 911 immediately if you notice any of these symptoms:

• When you have a strong allergic reaction or hives to a substance that you’ve been previously exposed that has a life-threatening effect on you
• When you have trouble breathing or when you experience wheezing
• When your voice is hoarse or if you start coughing suddenly
• If you have trouble swallowing, if you experience slurred speech or drooling
• If you suspect that your child is in a life-threatening emergency situation

Call the Doctor Immediately or Go to the ER

Go to the ER or call the doctor if you notice any of these symptoms:

• If the hives occur after ingesting a high-risk food such as nuts, shellfish, eggs, or fish
• If hives occur after taking a medicine, especially a prescription medication
• If a child under 1 year of age has hives all over its body
• If the child looks and acts unusual and sick

Call the Doctor in the Next 24 Hours

You should call the doctor within 24 hours if you notice these symptoms:

• If you get hives after taking an over-the-counter medicine
• If your eyes are swollen shut or if they itch profusely
• If you experience fever or swelling of the joints
• If you have stomach pain or vomiting

Call the Doctor During Normal Office Hours

Call the doctor during his usual office hours if you notice any of these symptoms:

• If the hives make hard for your child to go to school or perform usual everyday activities
• When you suspect that food could be the cause of hives
• If you had hives three or more times without a clear cause
• If the hives last for over a week