Allergies are very common – affecting 50 million people in the US. An allergy occurs when the immune system mistakes a harmless foreign substance as harmful. Such substances can include anything from pollen to foods like peanuts. Histamines are released around the body which cause various reactions – which may vary from mildly itchy eyes to life-threatening symptoms like anaphylaxis.
It’s worth getting an allergy diagnosed even if it’s not severe. A diagnosis could help you to get treatment and could help medical professionals if you ever do have a serious reaction. The following guide explains more about allergies including triggers, symptoms and treatment.
What are the most common allergy triggers?
The body can become allergic to pretty much anything. However, there are a few triggers that are more common than others.
Some of the most common allergy triggers include:
- Tree and grass pollen (known as hayfever)
- Animal fur (the most common being cats and dogs)
- Dust mites (typically from dust on sofas or mattresses)
- Certain foods like peanuts, milk and eggs
- Insects stings and bites (the most common being bees)
- Specific medication ingredients like penicillin
- Specific materials including metals or latex
Different triggers can often cause different allergic reaction symptoms, depending on how they interact with the body. For example, hayfever is more likely to cause itchy eyes than a food allergy, which is more likely to cause digestive problems or a swollen tongue.
What are the symptoms of an allergic reaction?
Allergic reactions can display many different symptoms. A few of the most common symptoms are listed below, along with some of the most common triggers in each case.
Red and itchy eyes are a common allergy symptom known as allergic conjunctivitis. In some cases, this may be accompanied by swelling of the eyes and blurred vision.
The two most common triggers for eye irritation are pollen and pet dander – if you’ve been outside during pollen season or been around cats or dogs, this may be the cause. Of course, there can be other triggers including certain types of make-up or even contact lenses.
Many people experience a runny nose, sneezing and post nasal drip – symptoms referred to allergic sinusitis. Swelling of the sinuses can also cause a headache in some cases.
The most common triggers for sinus irritation are pollen, pet dander and dust mites. However, things like smoke, mould or even scents can also trigger this reaction.
Many people develop itchy rashes or hives on their skin. The medical term for this is urticaria. Some people may also develop areas of dry and scaly skin – a type of eczema known as contact dermatitis.
A variety of different triggers can cause hives including food allergies, medications and insect bites. Contact dermatitis is more likely to be due to physical contact with allergen substances like metals (particularly nickel or cobalt), dust mites or certain cosmetic ingredients in makeup or dyes. In some cases, allergies may cause both, as is sometimes the case with latex.
Another common allergic reaction symptom is swelling known as angioedema. This can affect various parts of the body including the eyes, the lips, the tongue, the hands, the feet or even the genitals. It is often accompanied by hives.
Swelling can occur with many allergies including food allergies, medication, insect bites and materials like latex. Some people even experience it with pet allergies. While generally not serious, it can accompany other serious symptoms. Swelling of the tongue and mouth can be serious if it affects breathing.
Diarrhoea, bloating, nausea, vomiting and stomach pain can all be symptoms of an allergic reaction. While this can be mild in some cases, it can be more serious in other cases.
These symptoms are generally the result of consuming an allergen substance such as a food or medication. Food allergies will usually be accompanied by tingling or swelling in the mouth.
Allergic asthma can be another symptom of a reaction. This typically results in wheezing or coughing. Many people experience difficulty breathing which may be mild to severe (the latter is usually a symptom of anaphylaxis, although it can occur on its own).
Some of the most common triggers of allergic asthma include dust mites and pet dander (particularly cats). However, there can be many other triggers including food allergies, medication, pollen, mold, tobacco smoke or even certain cleaning chemicals.
Anaphylaxis is the most life-threatening allergic reaction you can have. A person will typically experience breathing problems rapidly, accompanied by confusion, light-headedness, clammy skin and in many cases loss of consciousness. It may be accompanied by many of the symptoms above – in some cases all of them.
Some allergy triggers are more likely to result in anaphylaxis than others. These include food allergies (most commonly certain nuts, seeds or fish), medication, insect bites/stings and materials like latex. The likes of pollen, pet dander and dust mites are less likely to result in anaphylaxis.
When is it not an allergy?
Many of the symptoms of an allergic reaction can occur for other reasons beyond an allergy.
With the likes of eye irritation and sinus irritation, you’ll usually be able to tell because the symptoms will go away when you are away from the trigger – if they persist, it’s more likely another medical condition such as an infection.
As for skin changes, hives are typically always caused by an allergic reaction, although there are exceptions like heat rash or contact with plants like nettles. Eczema can have much more triggers which may not necessarily be the result of an allergy. It’s possible eczema may be an underlying condition, in which cases it could be triggered by stress, temperature changes and even washing too regularly. This guide Eczema: Causes, Treatment and Prevention offers more information.
Swelling around the body can of course be caused by inflammation following an injury. In such cases, you’ll usually know from the pain that it’s not an allergic reaction. Stress can also cause excessive swelling for some people.
As for digestive issues, there are all kinds of causes from infections to food poisoning. A common misconception that many people make is mistaking an intolerance for an allergy. Intolerances can develop with certain food ingredients such as lactose or gluten just like allergies and display many of the same symptoms – but they are not actually the same. Food allergies will typically cause tingling in the mouth or swelling and possibly other symptoms like hives. Intolerances only affect the digestive system and symptoms may be slower to kick in. This post at Very Well Health offers more information about intolerances.
Finally, asthma may not always be caused by an allergy. Asthma can be a symptom of an infection, in which cases it’s likely to be more long-term. Asthma can also be an underlying health condition that may be triggered by stress, exercise or poor air quality. It’s important to consider your environment to determine if it is an allergy.
What causes an allergy – and can it develop at any age?
Allergies can develop at any age. Most people are born with them or develop them as a child. However, some people develop allergies as a young adult and even in later life.
Experts do not know for certain what causes an allergy to develop. For whatever reason, the immune system starts to see a foreign body as harmful. The first allergic reaction will usually be mild and subsequent reactions may get more serious. That said, there are cases where the first reaction may be a serious one.
You are much more likely to develop a new allergy if you already have an existing one. Generally, people with food allergies are more likely to develop other food allergies. Similarly, people with allergies to certain materials may develop allergies to other materials, and people with pet allergies may develop allergies to other animals.
How should you treat an allergy?
It is uncertain as to whether you can cure an allergy. Some people have succeeded in overcoming allergies through very careful exposure therapy and some people have grown out of allergies, but there is no scientifically approved cure.
Most people have to learn to live with allergies, which typically involves finding ways to reduce symptoms when an allergic reaction occurs. This usually involves taking medication known as antihistamines to rid the body of histamines (the chemicals that trigger the reaction). A few treatments include:
- Antihistamine tablets: These are swallowed and can be used to treat a variety of mild symptoms including eye irritation, sinus irritation and hives.
- Antihistamine creams: These creams are used to treat skin changes such as hives and are applied directly to the affected area. They are not recommended for contact dermatitis in which prescribed corticosteroid creams are better suited.
- Antihistamine nasal sprays: These can help to relieve allergic sinusitis and come in the form of a nasal spray.
- An inhaler: If you experience allergic asthma, you may want to see a doctor about getting prescribed an inhaler to help relieve breathing problems.
- An Epinephrine injection (EpiPen): This is an injection of adrenaline that is typically required to treat anaphylaxis. If you have experienced anaphylaxis before, a doctor will usually prescribe you an EpiPen. This should be carried around with you at all times and used as soon as you start to experience an allergy.
Some forms of allergic reaction may be worth seeing a doctor or even ringing an ambulance for. If you or someone else experiences anaphylaxis and neither one of you has access to an EpiPen, it’s worth calling an ambulance to get emergency treatment. Similarly, if you are having trouble breathing, you may want to call an ambulance or get someone to drive you to a hospital for emergency treatment. Other symptoms that don’t go away and are troubling you may be worth seeing a doctor for.