Hives (urticaria): causes, microbiome and how probiotic bacteria can help

Hives, medically known as urticaria, are a widespread skin condition that affects many sufferers with sudden itching and red welts. Despite their frequent occurrence, the condition is often mysterious: the causes are diverse and not always clear, treatment can be difficult, and symptoms significantly impair quality of life. In recent years, a previously underestimated factor has become the focus of research: the microbiome, the community of microorganisms on our skin and in our bodies. It has been shown that a healthy microbiome can modulate immune responses and thus plays an important role in hives. In this article, we examine the development of hives, the role the microbiome plays in this process, and how probiotic bacteria can support treatment.

What is hives?

Hives (urticaria) is a skin condition characterized by the appearance of wheals—transient, red, itchy bumps on the skin. These wheals can appear and disappear within minutes to hours. They are often accompanied by severe itching, sometimes also by burning or pain.

The main distinction is:

• Acute urticaria : Symptoms last less than six weeks.

• Chronic urticaria : Symptoms last longer than six weeks and often recur over months or years.

The hives are caused by local dilation of the blood vessels in the skin, resulting from the release of inflammatory mediators such as histamine. This causes fluid to penetrate the tissue, leading to the typical swelling.

Causes of hives

The triggers are diverse and often difficult to identify. Common causes include:

• Allergic reactions to food, medications, insect bites or pollen.

• Infections such as colds or urinary tract infections.

• Physical stimuli such as cold, heat, pressure or sunlight.

• Autoimmune processes in which the immune system attacks the body's own tissue.

• Stress and psychological strain.

• Idiopathic urticaria when no identifiable cause is found.

Certain diseases such as thyroid disorders or chronic infections can also promote hives.

How does hives develop at the cellular level?

Mast cells play a key role in hives. These immune cells are located in the skin and contain granules containing histamine and other inflammatory substances. When triggered, these mediators are released, leading to vasodilation, increased vascular permeability, and the typical symptoms.

Especially in chronic urticaria, it is suspected that autoantibodies against mast cells or their receptors permanently activate the cells.

The microbiome – an underestimated factor in hives

Traditionally, hives were primarily considered an immunological reaction. However, in recent years, the microbiome has gained increasing importance.

What is the microbiome?

The microbiome encompasses all microorganisms—bacteria, fungi, and viruses—that colonize our bodies. Huge communities of microbes live on our skin and in our gut, in particular, and maintain a symbiotic relationship with us.

These microorganisms are important for:

• The barrier function of the skin.

• The modulation of the immune system.

• Protection against pathogenic germs.

How does the microbiome affect skin and hives?

In hives, studies have observed that the diversity and composition of the skin microbiome is disrupted. Dysbiosis—that is, an incorrect colonization or imbalance—can weaken the skin barrier and dysregulate the immune system.

The following mechanisms are relevant:

• Impaired barrier function : A lack of beneficial bacteria can make the skin less resistant.

• Overactivation of the immune system : Incorrect colonization can promote inflammation and sensitize mast cells.

• Promoting inflammation : Certain types of bacteria can stimulate the release of inflammatory mediators.

• Connection with the intestinal microbiome : The balance of the intestinal flora also influences the immune response of the skin, as the intestine and skin are connected via the immune system.

Scientific findings: Microbiome and urticaria

Several studies indicate that patients with chronic urticaria have reduced microbiological diversity on the skin and in the gut. Certain probiotic genera such as Lactobacillus and Bifidobacterium are often reduced.

Dysbiosis can destabilize mucosal barriers and the immune system, which in turn promotes an overreaction such as hives.

Probiotic bacteria: A new therapeutic approach

Probiotics are live microorganisms that, when taken in sufficient doses, have health-promoting effects. They may help with hives on several levels:

• Restoring the microbial balance on the skin and intestines.

• Modulation of the immune system by promoting anti-inflammatory messengers.

• Strengthens the skin barrier , thereby triggering fewer allergic reactions.

• Reduction of stress and inflammation as the microbiome communicates with the nervous system.

Studies on probiotics for hives

Some clinical studies show that the administration of certain probiotic strains (e.g., Lactobacillus paracasei and Lactobacillus rhamnosus GG , Bifidobacterium lactis ) can alleviate the symptoms of chronic urticaria. Patients report less itching, fewer hives, and an improved quality of life.

In animal models, it has been observed that probiotics inhibit mast cell activity and thus reduce the inflammatory response.

Table: Microbiome and hives – influence and possible effects of probiotic bacteria

Practical recommendations for those affected

Anyone suffering from hives should consider the importance of the microbiome in addition to conventional medical treatment. The following approaches can help:

• Use probiotics in a targeted manner : preferably in consultation with a doctor or nutritionist.

• Microbiome-friendly skincare : Avoid harsh soaps and chemical additives.

• Healthy diet : Rich in fiber and fermented foods to support the gut microbiome.

• Stress management : Stress negatively affects the microbiome and immune function.

• Regular exercise to promote a healthy immune system.

Conclusion

Urticaria is a complex disease in which the immune system, environmental factors, and increasingly the microbiome play a crucial role. A disrupted skin and gut microbiome can promote the development and progression of urticaria by dysregulating immune responses and weakening the skin barrier.

Probiotic bacteria offer a promising complementary therapeutic approach. By restoring a healthy microbiome, they can reduce inflammation and modulate mast cell activity, thus alleviating the symptoms of hives.

The future of urticaria treatment will therefore likely be increasingly based on a holistic approach that encompasses both microbial health and classical therapeutic measures.