Most acute allergic reactions occur within seconds/minutes after exposure to the allergen. Some reactions can take place after a couple of hours, particularly if it concerns food allergy. Rarely, reactions develop after 24 hours

Source: https://medlineplus.gov/ency/article/000005.htm

An allergic reaction may last from a few minutes to several days, depending on the cause, type, and seriousness of the reaction from a few hours to a few days. Some allergic reactions may take two to four weeks to get any relief, even with treatment.

Source: https://www.medicinenet.com/how_long_does_an_allergic_reaction_last/article.htm

Allergies can affect anyone. You’re more likely to have or develop allergies, especially if your biological parents may also have allergies.

Source: https://my.clevelandclinic.org/health/diseases/8610-allergies

Most allergies develop in childhood; however, they may remain dormant, but may be reactivated if re-exposure to certain allergens occur later on in life.

Source: https://www.healthline.com/health/allergies/can-you-develop-allergies#causes

There is currently no cure for allergies. Allergies are usually a lifelong disease. People can treat their allergy symptoms with medicine and adjust their everyday activities to minimize their exposure to certain allergens.

Source: https://www.medicalnewstoday.com/articles/how-to-get-rid-of-allergies

Anaphylaxis is the most critical and possibly fatal end type of allergic reaction. It’s difficult to accurately report the number of people who died from anaphylaxis.

Source: https://www.achooallergy.com/blog/learning/allergy-frequently-asked-questions-faq/#faq4

A true food allergy affects your immune system. Even a small amount of food may trigger a range of symptoms such as an itchy sensation inside the mouth, throat, or ears, a raised itchy red rash, swelling of the face, around the eyes, lips, tongue, and roof of the mouth, or vomiting. These symptoms can be life-threatening. In comparison, food intolerance often affects your digestive system.

Source: https://www.mayoclinic.org/diseases-conditions/food-allergy/expert-answers/food-allergy/faq-20058538

Allergies may be diagnosed with allergy skin tests or blood tests which may reveal the presence of certain antibodies. Furthermore, your family's medical history can also be thoroughly analyzed with a full screening for an accurate diagnosis.

Source: https://www.achooallergy.com/blog/learning/allergy-frequently-asked-questions-faq/#faq4

https://www.allergy-clinic.co.uk/allergies/introduction-to-allergy/frequently-asked-questions/

Hay fever is usually worse between late March and September, especially when it's warm, humid, and windy. This is when the pollen count is at its highest.

Source: https://www.nhs.uk/conditions/hay-fever/

A climate change may lengthen the UK pollen season and potentially make pollen concentrations higher. It’s possible that climate change can lead to changes in the strength of pollen. The UK is also facing a threat from changes in the geographical distribution of allergenic plants, due to climate change, with invasive species such as ambrosia being on the watch list. A single ragweed plant can produce a billion grains of pollen per season and its pollen causes strong allergic reactions.

Source: https://ukhsa.blog.gov.uk/2016/05/04/will-climate-change-make-the-effects-of-pollen-worse/

As the name suggests, First-generation antihistamines, such as chlorpheniramine and diphenhydramine were the first kind to get approved by the Food and Drug Administration (FDA), and became available on the market in the early 1940s. Second-generation antihistamines, like fexofenadine (the active ingredient in Histallay), became available for general use in the 1980s. One of the key attributes of first-generation antihistamines that differentiate them from second-generation antihistamines is that they cross your blood-brain barrier (BBB) that results in drowsiness.

Source: https://www.webmd.com/allergies/difference-between-first-generation-antihistamines-second-generation-antihistamines

Your brain is the control center of your body and it needs to be protected from the entry of unwanted substances such as toxins, harmful bacteria and viruses. The blood-brain barrier (BBB) is a protective layer that acts like a gatekeeper and keeps these harmful substances out and only allows the transfer of useful substances such as nutrients, oxygen and essential molecules.

First-generation antihistamines, while effective in blocking the action of histamine, also have a significant drawback. They can cross your blood-brain barrier (BBB) and enter your brain. This leads to the feeling of drowsiness, sedation and sometimes can make you feel dizzy or confused. In simple terms, they make you feel sleepy and tired because they affect the normal functioning of the brain.

On the other hand, Second-generation antihistamines, like Histallay, were designed to have less impact on the brain. They are more selective in their action, and have limited ability to cross the blood-brain barrier (BBB). As a result, they cause minimal or no drowsiness, making them more suitable for daytime use.

Source: https://my.clevelandclinic.org/health/body/24931-blood-brain-barrier-bbb

Histallay 120 mg is indicated in adults and children 12 years and older for the relief of symptoms associated with seasonal allergic rhinitis: sneezing, runny nose, itchy, watery eyes, and itchy nose or throat.

Fexofenadine hydrochloride (an antihistamine) is the active ingredient in Histallay®

No, Histallay® is available over the counter in pharmacies and all major supermarkets.

Histallay® may start to work within 60 minutes.

Histallay® provides 24-hour relief, all day and all night.

Histallay® can be taken with or without food.

Any time of day works and Histallay® will continue to work for 24 hours.

The active ingredient in Histallay® (fexofenadine hydrochloride) is a second-generation antihistamine which has been shown to least likely to cause drowsiness in the majority of people.

It is unlikely that Histallay® will produce an effect on the ability to drive or use machines. However, in order to identify sensitive people who have an unusual reaction to medicinal products, it is advisable to check the individual response before driving, dealing with machinery, or performing complicated tasks.

If you are pregnant or breastfeeding, you should consult with your doctor before taking this medicine.

Histallay® 120 mg should not be used in children under 12 years of age. In children from 6 to 11 years of age: fexofenadine hydrochloride 30 mg tablet (prescription only medicine) is the appropriate dosage in this population.