What are Hives?
Hives can be as small as a dime or much larger. In some cases, a number of outbreaks will join together into something known as a ‘plaque.’ They can appear anywhere on the body, including the lips, tongue, throat, and ears, and often resolve on their own. In some rare cases, the angioedema associated with hives can cause swelling in the throat or lungs, resulting in some difficulty breathing.
Hives are a very common skin condition, estimated to occur in 1 in 5 people at some point in their lives. Hives are not contagious, though their presence can cause frustration and aggravation for patients due to the unsightliness of the condition and its associated itching. Hives are triggered by any number of factors, although it can be difficult to determine what exactly has triggered an outbreak of the condition.
The duration of the condition varies largely from one outbreak to the next. In some cases, an outbreak may last hours, while another outbreak could last for weeks.
What Causes Hives?
Hives can be caused by any number of triggers, including allergic reactions, drugs, certain chemicals in foods, or environmental triggers. Hives caused by stress are also common. Oftentimes, it can be difficult to attribute a single cause to an outbreak of hives.
When the body encounters one of these triggers, it releases a chemical known as a histamine. This histamine then triggers small leaks of blood plasma out of very small blood vessels in the skin, resulting in both hives and, on occasion, angioedema.
There are both acute and chronic versions of hives. Acute urticaria lasts less than six weeks, while chronic urticaria lasts longer than six weeks. With acute cases, it is typically easier to identify a trigger. Triggers commonly include food, medicine, insect bites, or even latex.
Causes of chronic hives may involve the same triggers as in acute cases, but can also stem from comorbid conditions related to the immune system, chronic infection, or hormonal disorders. In some scenarios, patients may experience what is known as physical urticaria in which the hives stem from direct contact with cold, heat, sweat, or pressure. This type of hives typically resolves quickly after exposure when the patient is no longer in contact with or aggravated by the triggering substance.
Common foods that can trigger hives include chocolate, nuts, fish, eggs, fresh berries, tomatoes, soy products, wheat, and milk. Unfortunately, fresh, whole foods are often more likely to trigger hives than foods that have been cooked. Hives can also be triggered by the additives and preservatives added to processed foods.
Medications can also trigger hives. NSAIDs, like aspirin and ibuprofen, can cause hives, as well as some high blood pressure medications, including ACE inhibitors. Common painkillers such as codeine have also been associated with the development of hives.
Finally, it may be a virus that causes hives in some patients. Viruses that can trigger hives include the common cold, urinary tract infections, strep throat, mono, and hepatitis. Causes of hives in adults can vary from causes in children, who are often more affected by viral triggers.
Frequently Asked Questions
What’s the Difference Between Hives and Rashes?
Hives are all rashes, but not all rashes are hives. One distinguishing characteristic is that many rashes do not itch, while hives are always itchy. Hives also have very distinct bumps, whereas rashes can be scaly, flaky, or involve blisters. Rashes can also often feel very hot to the touch.
How Long Do Hives Last?
Hives can last an hour or two, or for as long as several weeks. Typically, hives caused from acute triggers, such as exposure to foods, resolve more quickly once the patient is no longer exposed to the trigger. Chronic cases lasting longer than six weeks may involve a secondary condition. In those scenarios, treating the other condition is an important part in resolving hives.
Can Stress Cause Hives?
Yes, stress can cause hives. It is a common trigger of urticaria in adults. Stress hives are particularly common in women who are in their 30s, 40s, and 50s. Anyone experiencing hives from stress can reduce symptoms by treating the hives and addressing any stress triggers in their lives.
Are Hives Contagious?
Hives are not contagious. They are triggered by an immune response in the body and the release of histamines. You will not develop hives on your skin if you touch the affected skin of another person.