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If you have lots of the thing you’re allergic to, does your body eventually get used to it? – Karen and Dawn, age 14 and nine, Manchester, UK
Thanks for your brilliant question, Karen and Dawn! As usual with science, there is not a simple answer. But the first thing to say is that if you know you are allergic to something, you must not purposefully go near it or eat it to try and make your allergy better. It won’t work and might make you very unwell.
Some people are allergic to things in the air, such as pollen, dust and animal hair. Other people are allergic to certain foods, or things that we touch.
When you are allergic to something, your body mistakenly thinks that the thing you are allergic to is going to cause you harm.
This triggers your immune system (which normally fights infections) to start fighting whatever you’re allergic to. Then you get symptoms, which are the signs that something is wrong in your body.
The symptoms could be anything from an itchy nose and sneezing to breathing problems or a skin rash. In the case of serious allergies, people may get a swollen tongue or throat, which can be very dangerous.
There are some very serious allergies that you must always be very careful with, because they can lead to a very serious medical problem called anaphylaxis.
The most common foods that cause anaphylaxis are nuts and eggs. People who have these allergies must carry a special injection with them all the time, in case they accidentally eat these things, and they always need to be extra careful around food.
Some less serious allergies, such as hay fever, might get better if you were stuck on an island for a long period of time with no medication. This is because our bodies can get used to the pollen that causes this allergy.
There are medical ways of testing this, which experts call “desensitisation therapy” or “immunotherapy”. This means that you are given a certain amount of the thing you are allergic to every day, until you become less sensitive to it. This should always be done with the help of a doctor, and it doesn’t work for all allergies.
There are some things that you might be intolerant to, but not allergic to. This means that when you eat it, you might get some tummy trouble, but it would not cause you any serious harm.
Milk is a really good example of this. There is a type of sugar in milk called lactose. To digest lactose, humans need a special chemical called an enzyme, which is made in our intestines.
When we are babies, we all produce lots of this enzyme because we only have milk. Some people stop making the enzyme altogether when they are adults and some people might just make a bit less of it. And some people will produce more or less of it depending on how much milk they drink.
That means that sometimes, if you haven’t had much milk for a while, then you have a lot, you might have a sore tummy. But you might also find that the more milk you have, the more of the enzyme your gut produces and the more milk you can enjoy without a tummy ache.
Only milk from animals (including humans) has the sugar lactose in it, anything that is made from plants like coconut milk, soya milk and almond milk does not contain any lactose.
But whether you’ve got an allergy or an intolerance, it’s very important to always follow your doctor’s instructions.
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