Symptoms of allergies

Rashes, sneezes, coughs and wheezes, a healthcare provider uses a tablet to explain the symptoms of allergies to the patient

This article is all about how to tell if you could be having an allergic reaction. We’ll take you through some of the common symptoms of allergies from watery eyes and a blocked nose to shortness of breath and skin rashes. How you experience allergy will be personal to you, depending partly on your trigger. So we’ve packed this article with links to information about specific allergies. And treatment options, of course. There’s lots to take in.

Symptoms of allergies: What the doc calls them

Most people have heard of hay fever and hives. And who doesn’t cough? So let’s start with the medical names for some common symptoms of allergies. It’ll help you decode the information that comes with any allergy medication.

  • Allergic rhinitis: A blocked or runny nose, plus sneezing. Seasonal allergic rhinitis, also known as hay fever, is linked to outdoor allergens such as pollen. Perennial allergic rhinitis means symptoms can be year-round. They happen indoors from allergens such as dust mites.
  • Allergic conjunctivitis: Irritation inside your eyelids and on the surface of the eyes makes them itchy, red and watery.
  • Allergic rhinoconjunctivitis: Sneezing, and a blocked and runny nose, plus itchy, burning, red and watery eyes.
  • Lower respiratory symptoms: cough, shortness of breath, tight chest and wheezing
  • Atopic dermatitis: Chronic or recurring condition also known as eczema where the skin becomes itchy, dry, cracked and sore
  • Skin reactions: Urticaria (hives), angioedema (swelling) or itchiness
  • Gut reactions (food allergy): Nausea, vomiting, bloating and diarrhea

Hay fever symptoms
aren't much fun

A sneezing man pink

What causes symptoms of allergies

Allergy symptoms are the outward sign that your body is trying to fight off a threat. Or at least, something it thinks is a threat. That could be pollen or peanut or another substance harmless to most people.

Humans do face plenty of real threats like viruses, bacteria, parasites and so on. It’s why your body has inbuilt protection. Your immune system is always on guard. It makes specific immunoglobulin (IgE) antibodies each time you meet a threat. These antibodies send histamine and white blood cells to flush out any intruder. Your immune system reacts the same way when you come into contact with an allergen. That’s an allergic reaction.

Are symptoms of allergies for life?

They may be. Or they may not. Allergies are complicated but there are some known knowns. For instance, your immune system starts to develop in the womb. And it goes on adapting to new threats throughout your life. This is why babies can have allergic reactions and may later grow out of them. And why grown-ups can start having allergic reactions or find their symptoms of allergies change. Your immune system is unique to you (obviously). But scientists have found a pattern in how allergic conditions often evolve. They tend to affect the skin first, move on to the stomach and then to the airways.

Symptoms of allergies: 3 common triggers

Many ordinary substances you come into contact with every day can trigger an allergic reaction. The allergens in this article fall into three groups:

Respiratory allergens

Symptoms caused by respiratory allergens

Pollen, dust mites, pet dander or mold can all make you feel as if you’ve got a cold. That’s allergic rhinitis, remember.


Allergy symptoms caused by food

Diarrhea, bloating, skin reactions and itching. In serious cases, you could have a life-threatening allergic reaction.

Insect venom

Allergy symptoms caused by insect venom

Pain, redness, swelling, flushing, hives and itching. May even cause a life-threatening allergic reaction.

Can symptoms of allergies be serious?

Most people with allergies will mostly get mild to moderate symptoms. But severe reactions are possible. You may have heard of anaphylaxis. It can be life-threatening and this is what to look out for:

  • Skin reactions, including hives and itching and flushed or pale skin
  • Drop in blood pressure (hypotension)
  • Constriction of your airways and a swollen tongue or throat, which may cause wheezing and trouble breathing
  • A weak and rapid pulse
  • Nausea, vomiting or diarrhea
  • Dizziness or fainting

Severe symptoms of allergy are more common with some triggers. These include medicines, food, insect stings and latex.

When to expect symptoms of allergies

Indoor allergies tend to be less dependent on the calendar. They can cause trouble any time, which is why they’re known as perennial or persistent. But seasonal allergies like pollen peak during certain months of the year.

  • Seasonal allergy symptoms

Tree pollen is the first of the seasonal allergies to trigger hay fever symptoms, often very early in the year. Grass pollen follows in the spring and summer. Ragweed and other weeds strike in the autumn.

  • Perennial or persistent allergy symptoms

Dust mites, pet and food allergies are perennial or persistent allergies. They can strike at any time of the year. Although dust mite allergy can be worse in the cooler months. Switching on the central heating often stirs up the allergens.

Man in work clothes blowing his nose at his desk. Dust mite allergy symptoms make it hard to focus on his job.

Dust mite
allergy symptoms

What is the allergy symptom threshold?

Everyone’s immune system is calibrated differently. You may start sneezing when allergen levels are low. That’s your allergy symptom threshold. Or you could have several allergies but only get a mild reaction (if any) until you meet all your triggers at once. The IgE antibodies work away quietly all year, reacting to cat or dog dander, dust mites or mold. Pollen season hits and the higher allergen levels push your immune system too far. Now you’ve got symptoms of allergies.

Symptoms of allergies from cross-reactions

Another allergenic protein can be so like your trigger that it puts your immune system on full alert too. It happens with tree, weed and grass pollen. So people with birch allergy might get allergic rhinitis from alder, hazel, hornbeam and oak pollen, as well as mugwort and grass. It’s not their main allergy but a cross-reaction.

Pollen allergies can also give you mild local symptoms when you eat certain fruit, vegetables, spices and nuts. For instance, ragweed cross-reacts with cantaloupes. This is pollen food syndrome or oral allergy syndrome.

The proteins in dust mite allergens and crustaceans are similar. As are cat dander and pork. Both cross-reactions are rare but they can cause severe symptoms. So ask your healthcare provider for advice, diagnosis or treatment if it happens. Also if you experience any kind of reaction when eating peanuts, tree nuts or soy.

Diagnosing symptoms of allergies

Hearing about your allergy symptoms helps your healthcare provider make the diagnosis. Many people use an allergy diary to keep track of the effect on their health. Information to include might be how often you get symptoms. Also, what you’re doing and where you are when they start. And what you think could be causing them.

A skin prick test or allergy blood test may be necessary to narrow down the possible trigger. Allergy tends to run in the family so you could ask about having your child tested if they’re getting symptoms too.

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Symptoms of allergies: treatment options

Your healthcare provider or allergist will find a treatment plan that works for you. Here are some questions to help you start that conversation:

  • How will allergies affect my daily life (work, home, social life and exercise)?
  • How can I control my symptoms of allergy?
  • Can you help me avoid my allergen?
  • What medications would you suggest for my allergy symptoms?
  • If relevant, how do I manage my allergy with other medical issues?

Antihistamines and corticosteroids can help with your blocked nose, watery eyes, itchy skin and so on. Many of these symptom-relievers are available over the counter. Others will need a prescription. These medications can also work as a preventative measure taken before you come into contact with your trigger.

What to do in a severe allergic reaction

People at risk of anaphylaxis usually keep an adrenaline pen or auto-injector nearby at all times. Adrenaline is the immediate on-the-spot treatment that can counteract a severe reaction. In fact, the advice is to carry two pens. You should also tell your family how to use them in case you need their help.

Anaphylaxis can strike very quickly and is always an emergency. Call for an ambulance if you recognize the severe symptoms of allergy described above.

Retraining the immune system to reduce symptoms of allergies

Only immunotherapy can bring long-term relief from symptoms of allergies. Your healthcare provider will be able to tell you if it’s right for you and help you through the process.

A full course of immunotherapy takes three to five years. It works by targeting the root cause of your allergy. Controlled repeated doses of your trigger gradually teach your immune system to stop seeing the substance as a threat. This can stop or greatly reduce your allergy symptoms. Imagine that, no more cough or sneezing, runny nose, mucus at the back of your throat...

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