Allergies are often associated with childhood, but they can develop at any point in life, sometimes seemingly out of nowhere. According to allergist Kelly Colas, any person can develop a new allergy at any time. Researchers have identified various factors that can trigger new allergies, including Covid-19, hormonal changes, and tick bites. These factors can cause the immune system to become confused, leading to the development of new allergies.
Covid-19 has been linked to an increased risk of developing allergic rhinitis and asthma. A 2026 study found that catching Covid-19 is associated with a significantly higher risk of developing these conditions. The immune system can become overwhelmed during a case of Covid-19, leading to inflammation and an increased risk of allergies. Other illnesses, such as respiratory syncytial virus and rhinovirus, can also have similar effects.
Treatments used to address common illnesses can also have unintended effects on the immune system. Antibiotic use has been linked to a subsequent risk of allergies, possibly due to the disruption of the delicate balance of the gut microbiome. The gut microbiome plays a crucial role in immune system function, and disrupting it can lead to confusion in the immune system, causing harmless substances to be seen as threats.
Pregnancy is another significant disruption to the immune system, and it can have unexpected effects on allergies. About a third of women with pre-existing environmental allergies find that they get worse after conceiving. Pregnancy rhinitis is a temporary condition that can occur during pregnancy, causing allergy-like symptoms such as sneezing, congestion, and runny nose. This condition is thought to be related to hormonal fluctuations.
Hormonal changes during menopause can also lead to the development of new allergies. Research suggests that women may experience new allergies after they hit menopause, possibly due to changes in estrogen and progesterone levels. These hormones can interact with the immune system in complex ways, leading to unexpected effects.
Tick bites can also cause new allergies to develop. The bite of a lone star tick, for example, can cause a reaction to red meat. This condition, known as alpha-gal syndrome, is becoming more common in the US as lone star ticks spread to new parts of the country. Diagnoses of alpha-gal syndrome have increased rapidly in recent years, with over 90,000 people diagnosed between 2017 and 2022.
Unfortunately, many people who develop sudden-onset allergies may not be able to overcome them. While some conditions, such as pregnancy rhinitis, may resolve on their own, others may be permanent. Understanding the causes of new allergies and how they develop is crucial for developing effective treatments and prevention strategies.
Key points
- Covid-19 has been linked to an increased risk of developing allergic rhinitis and asthma.
- Hormonal changes during pregnancy and menopause can lead to the development of new allergies.
- Tick bites can cause new allergies to develop, including alpha-gal syndrome.
