Hives (urticaria) in adults are triggered by some of the same factors that trigger hives in children and teenagers. Among these triggers or causes of hives in adults are allergic reactions. Adults may have allergies to such substances as medication, food, preservatives and pet dander. In allergic responses to these triggers (either from ingesting or touching the allergens), these adults develop hives on their skin within any amount of time between a few minutes and a few hours.

Allergic hives typically present as acute hives. As long as one is able to remove the allergen from his or her environment, the hives symptoms ultimately resolve and do not recur. If one should fail to identify the substance, then it is possible to be exposed to it again and again, resulting in hives episodes without relief. This could easily happen with a substance like food coloring or a food preservative. Most people are unaware that they ingest these substances when they eat processed foods. Hence, they are not likely to know which foods contain them or that they are repeatedly exposing themselves to allergens.

Autoimmune disease is another cause of hives in adults. Various autoimmune disorders, including lupus and thyroid disease, are associated with outbreaks of chronic hives. Some studies on the connection between hives and thyroid disease have shown greater prevalence of thyroid autoantibodies among patients with hives. Upon treatment for thyroid disease, these patients’ hives have cleared. The studies, therefore, indicate a definite connection between autoimmune disease and the development of hives, even though the mechanisms behind such a connection remain largely mysterious.

Stress and Infection as Triggers of Hives in Adults

Stress is yet another common trigger of hives in adults. This should not come as a surprise, given the high levels of stress endured by adults at their places of work and in other aspects of life. Younger age groups do experience stress. However, children tend to be shielded from the extremes of stress by the adults in their lives.

When urticaria in adults is associated with stress, it tends to present as a chronic condition. If the stress is not addressed, then the urticaria endures. In addition, chronic stress weakens the immune system, increasing patients’ vulnerability to infection and to psoriasis, an autoimmune disease which manifests as a skin condition.

Various infections, including viral, bacterial, fungal and parasitic infections can also be considered reasons for hives in adults. These infections vary. They may include urinary tract infections, infections of the gastrointestinal tract, ENT infections, upper respiratory tract infections and infections of the dental area. When these infections are successfully treated, the associated hives vanish, indicating that there is a connection between infection and the prevalence of hives.

The most common causes of hives are allergic reactions that trigger an immune system response. The immune system acts as if there is something foreign in the body and signals the body to release histamine to fight it. Some of the more common causes of hives may be:

• Insect bites
• Food allergies
• Temperature extremes
• Infections (fungal or viral)
• Food additives
• Tight clothes rubbing skin or repeated stroking of skin causes hives

These are very broad but common skin hives causes, particularly when looking for what causes hives of the acute variety.

What causes hive rash

The causes of hives, or what causes skin hives are well known. It is the actual trigger or triggers that have patients and doctors perplexed. It is the release of histamine that causes the small blood vessels to leak fluid. This fluid accumulates in the skin and is actually what causes the hives and the associated rash and wheals. But the trigger is never found in half the cases and chronic hives causes are even more difficult to figure out. The symptoms are usually straightforward to treat, but the causes of hives being so difficult to detect means that what causes rashes and hives will remain a mystery for many.

What causes hives in adults?

The causes of hives in adults, when they can be determined, are usually related to a drug the adult is taking or a reaction to food. Food allergies are where the difference in hives causes in adults differs most from children. In adults, the most common food causes of hives are shellfish, fish, peanuts, and other nuts.

This may be because are more likely to be on drugs or other medications and more likely to eat fish and shellfish than children. Painkillers are a common trigger and more adults use painkillers than children.

What are the causes of hives in children?

Viral infections are generally recognized as the most common causes for hives in children

When the causes of hives in children are narrowed down to food, the food causes in children tend to be mostly milk, eggs, soy, wheat, and peanuts or other nuts. Again, this may be anecdotal since children tend to eat more dairy products than adults, and by the time one becomes an adult, they will have likely already figured out that these dairy products are one of the causes of hives and are already avoiding them.

These are the main differences between what causes hives in children and adults. Most of the other identifiable causes are the same and treatment is usually the same for both adults and children. But you shouldn’t be surprised if the causes of hives is never identified, as the majority never are.