What's the Difference Between an Allergy and a Sensitivity?

Mary McMahon
Mary McMahon

The primary difference between an allergy and a sensitivity is that an allergy is characterized by an immune system reaction to a substance, while a sensitivity involves no immune response. Both, however, can be quite serious, as can intolerances, and a range of symptoms can be caused by allergies, sensitivities, and intolerances. For this reason, it is a good idea to see a doctor about symptoms which appear to be linked to exposure to certain substances, to figure out precisely what is going on.

A sensitivity could manifest itself through a runny nose.
A sensitivity could manifest itself through a runny nose.

In the case of an allergy, the immune system learns to attack a particular substance for an unknown reason. In order for an allergic response to develop, someone must be exposed to the substance at least once before the response will manifest. A classic example of an allergic reaction is to peanuts, in which the immune system regards peanuts as harmful, and goes into overdrive when someone consumes peanuts or is exposed to peanut products.

Eczema is common with allergies.
Eczema is common with allergies.

Some common symptoms linked with allergic reactions are dermatological symptoms like eczema and hives, respiratory problems, anaphylaxis, rhinitis, and shock. These symptoms may emerge immediately, or within a few hours, depending on the type of allergy and the severity of the immune system response.

Hives typically stem from an allergic reaction.
Hives typically stem from an allergic reaction.

A sensitivity involves no immune system response, but it can still yield a multiplicity of symptoms, ranging from issues in the digestive tract to neurological problems. Some of the issues associated with sensitivities can become life threatening, especially if someone is exposed to a substance repeatedly, which is why it is important to be aware of sensitivities. Commonly, sensitivities manifest in the form of abstract symptoms like fatigue, weight loss, constantly runny nose, and a general feeling of being unwell, which can make it challenging to track down the offending substance.

In the case of an intolerance, someone's body lacks the substances necessary to process something. A well known example of intolerance is lactose intolerance, caused by a lack of the enzyme needed to digest milk. When someone with lactose intolerance consumes dairy products, the results can be quite uncomfortable and often very unpleasant, as his or her digestive system struggles to cope with the milk.

Allergies, sensitivities, and intolerances should all be taken seriously. In some cases, there are treatments available which can help to reduce the severity of the response to something, and in some cases eliminate the response altogether. In other instances, there may be no treatment available, in which case it is important to be outspoken to avoid exposure to the offensive substance.

A topical cream can be applied to alleviate itchy skin.
A topical cream can be applied to alleviate itchy skin.
Mary McMahon
Mary McMahon

Ever since she began contributing to the site several years ago, Mary has embraced the exciting challenge of being a wiseGEEK researcher and writer. Mary has a liberal arts degree from Goddard College and spends her free time reading, cooking, and exploring the great outdoors.

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Discussion Comments


I can't take perfume, cologne or any scented products. When it's on my skin I break out in hives or a rash. When I'm just around it I get a headache and can't concentrate very well. I'm not dizzy; I just can't concentrate. And once I opened the dish detergent box and I started coughing and it continued for a few minutes after I left the room. Can anybody tell me whether I am allergic or just highly sensitive?


I found out the hard way that I am allergic to bee stings after having a bad reaction when I was stung while mowing.

Now I have to carry an pen with me to use if I ever get stung again. My cousin told me he knew a beekeeper who had this same problem and received allergy shots to help him so he could continue to raise bees.

He still carries a pen with him just in case, but has been able to build up immunities to the stings. I think I will just plan on staying as far away as possible.


I have several friends who suffer from allergies especially during the spring and fall. Most of them had hay fever and were allergic to trees and flowers. Imagine my surprise when I found out I had dust allergies! I had never heard of that before.

Although I am not the best housekeeper, I am by no means a bad one, and the thought of trying to keep all that dust away was overwhelming to me. I wondered how in the world can you do that?

I found out that most of the time, the dust is a combination of many things such as pollen and pet dander. I have to vacuum more often, make sure my bedding is changed on a regular basis, and have mostly hard wood floors in my home instead of carpeting.


I always wondered if there was a difference between between being allergic to something or just having a sensitivity to it. After years of stomach problems I finally found out that I was lactose intolerant.

This made sense when I started thinking about it, that most of my problems came after eating ice cream and cottage cheese. I never have been much of a milk drinker, so didn't think I really consumed that many dairy products.

When you learn you are allergic to something and start reading labels, it is amazing to find out how many products actually contain dairy.

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