Allergy is a response of the immune system that identifies as harmful some substances that do not usually affect most people. These allergic reactions can be of various types according to the substance to which it reacts (allergen) and according to how it presents itself, although there are some allergies that are more frequent and reason for consultation in Allergology.
Respiratory allergies
The main respiratory allergic reactions are:
- Allergic rhinitis: this is the most frequent allergy, affecting 25% of the population. It is usually associated with other allergic diseases such as asthma, dermatitis or conjunctivitis and the main symptoms are mucus, nasal congestion, itchy nose, eyes, ear, palate and throat, sneezing, among others.
- Allergic asthma: it is the second most frequent allergy and is associated with allergic rhinitis in up to 80% of cases. It is characterized by bronchial inflammation and obstruction, the symptoms of which are shortness of breath, cough and chest tightness and wheezing.
Dermatological allergies
Dermatological allergic diseases present skin alterations. Among these, the following stand out:
- Urticaria: this is a skin disease characterized by the appearance of itchy wheals (bumps) or welts and affects more than 10% of the population at some time in their lives. When it affects deeper parts of the skin, producing inflammation of the lips and eyelids, it is called angioedema.
- Atopic dermatitis: characterized by dry skin that causes intense itching, scratching, redness and eczema (desquamation). It most often affects children, although it can also affect adolescents and adults.
- Allergic contact dermatitis: this is caused by direct skin contact with substances such as perfumes, hair dyes or metals (chromium, cobalt, nickel), among others. It is diagnosed by epicutaneous tests, also called patch tests, which consist of applying a patch containing 33 different allergenic substances to the skin (usually on the back) so that they come into contact with the immune system for 48 hours. Once this period of time has elapsed, the patch is removed and the reactions that have occurred are analyzed.
Drug Allergy
Adverse drug reactions (ADRs) are a heterogeneous group of reactions that occur when taking medications. It should be noted that not all reactions to drugs mean an allergy, so it is important not to confuse the concepts so that someone is not mistakenly considered allergic to drugs.
Thus, any drug can produce an allergic reaction, although the most frequent are the antibiotics of the Penicillin group and the anti-inflammatory drugs.
It is important that, if one has had a reaction to any medication, the name of the drug, why it was prescribed, what symptoms it produced, how it was administered and how long it took for the reaction to appear since it was taken. All this information is very useful to make the diagnosis of the allergy easier and the result safer.
Food allergy
This allergy can occur at any age and for any food. In children, the most frequent foods are cow’s milk, eggs and fish, while in adults they are seafood, nuts and fruits. Symptoms can be very varied, although the most frequent are:
- Digestive symptoms (vomiting, nausea and abdominal pain).
- Itching or swelling of the lips
- Skin symptoms (urticaria and atopic dermatitis)
- Respiratory distress
- Rhinitis
- Anaphylaxis (in the most severe cases).
It is important to identify the causal food in order to be able to recommend to the patient how to avoid taking it. To diagnose it, it is necessary to have a thorough clinical history, to perform allergic skin and laboratory tests and, in some cases, tolerance or provocation tests.
It should be noted that not all reactions to food are due to food allergy, as sometimes they may be due to other immunological mechanisms and other times they may be non-allergic based intolerance reactions, such as lactose intolerance.
Insect sting allergy
The most common reactions after a bee or wasp sting are swelling and redness in the area of the sting, although in some people it can produce more severe symptoms that may even endanger the patient’s life.
Anaphylaxis, the most serious allergy
Anaphylaxis is a generalized allergic reaction that can even endanger the patient’s life. The symptoms can be very varied, from cutaneous to respiratory, digestive or cardiovascular, as well as the causes, which can be insect bites, allergies to drugs or food, radiological contrast media, or the confluence of several factors.
Identifying the cause can be complicated in some cases, so once again, it is important to study the clinical history thoroughly to diagnose the allergy correctly. It is also important to instruct the patient to use adrenaline or other medications to control further episodes that may occur in the future.