Does one of your friends react bizarrely after ingesting a particular food? Have you tried asking anyone why he has a swollen lip and he answers you that he ate something he is allergic to? Do you know anyone who is said to be allergic to something?

Well then do not puzzle yourself. Although allergies may not be normal, it is not uncommon. The signs and symptoms of an allergic reaction may vary in different individuals. For example, one might have a swollen lip or others may have rashes that are red and itchy otherwise known as urticaria; some may have trouble breathing. You will know that it is an allergic reaction when it takes place right after that particular individual is exposed to a particular allergen.

Anything that causes an allergic reaction is known as an allergen and it comes in various forms. Some common allergens are food, cosmetics and medications. Why do some people have an allergic attack? It is because their immune system is reacting abnormally. It sees the allergens as an invader or an enemy when in fact it is totally harmless.

When the immune system detects something harmful it releases antibodies to ward off invaders. In people with allergies, their immune system sees the commonly not harmful substances as enemies causing it to release antibodies that would trigger a series of events and the end result are those itchy red spots and swollen lips or eyelids. Being aware of what you are allergic to will help you steer clear from any allergic reaction. Here are some of the most common allergens.

1. Medications. This only doesn't mean antibiotics it could also include NSAIDs and pain relievers. Although to some people medicines can be of great help, to those with hypersensitivity to a particular type of drug it could mean trouble. Not everyone is allergic to medications so in case you have a known allergy to some of these drugs better avoid taking them.

In case of antibiotics, especially those administered directly into the blood stream, a skin test is performed. In a skin test, a small amount of antibiotic is injected beneath the skin to test if that individual reacts to it and in case the results are positive that particular antibiotic will not be given.

2. Make-up. Every individual's skin is unique. There are some people that have very sensitive skin that even though a particular make-up is labelled as hypoallergenic she will still have an allergic reaction. We all know that cosmetics are made up from various ingredients and some of these ingredients may trigger one's allergies.

3. Food. All types of food have the capacity to produce an allergic reaction especially if one is sensitive to it. Seafood and chicken are always on top of the list. People who have allergies to a particular type of food should avoid eating it because he or she will surely end up with a swollen lip or any other untoward reaction.

4. Pets. We all know how some people are allergic to dogs, cats and even monkeys. Usually, people with pet allergies react by sneezing or coughing. When you know someone who is allergic to any kind of pet it would be best to keep that particular pet away. Hairy pets usually cause an allergic reaction that is why we always hear people saying that they are allergic to cats especially those with fluffy hair.