Antihistamines, also known as anti-allergens, are remedies used to treat allergic reactions, such as hives, runny nose, rhinitis, allergy or conjunctivitis, for example, reducing the symptoms of itching, swelling, redness or runny nose.
Antihistamines can be classified into:
- Classic or first generation: they were the first to be introduced to the market and have more side effects, such as severe drowsiness, sedation, fatigue, changes in cognitive functions and memory, because they cross the central nervous system. In addition, they are also more difficult to eliminate and, for these reasons, should be avoided. Examples of these remedies are Hydroxyzine and Clemastine; Non-classic or second generation: these are drugs that have a greater affinity for peripheral receptors, penetrate less in the central nervous system and are eliminated more quickly, thus presenting fewer side effects. Examples of these remedies are cetirizine, desloratadine or bilastine.
Before starting treatment with antihistamines, you should speak to the doctor, so that he recommends the most appropriate for the symptoms presented by the person. Learn how to recognize allergy symptoms.
List of major antihistamines
Some of the most used antihistamine drugs are:
| Antihistamine | Commercial name | Causes sleep? |
| Cetirizine | Zyrtec or Reactine | Moderate |
| Hydroxyzine | Hixizine or Pergo | Yes |
| Desloratadine | Leg, Desalex | No |
| Clemastina | Emistin | Yes |
| Diphenhydramine | Caladryl or Difenidrin | Yes |
| Fexofenadine | Allegra, Allexofedrin or Altiva | Moderate |
| Loratadine | Alergaliv, Claritin | No |
| Bilastine | Alektos | Moderate |
| Dexchlorpheniramine | Polaramine | Moderate |
Although all substances can be used to treat various cases of allergy, there are some that are more effective for certain problems. Therefore, people who have recurrent allergy attacks should consult their general practitioner to find out which medicine is best for them.
Which can be used in pregnancy
During pregnancy, the use of medications, including antihistamines, should be avoided as much as possible. However, if necessary, the pregnant woman can take these remedies, but only if recommended by the doctor. Those considered to be safer in pregnancy, and in category B, are chlorpheniramine, loratadine and diphenhydramine.
When not to use
Generally, antiallergic remedies can be used by anyone, however, there are some cases that need medical advice such as:
- Pregnancy and breast-feeding; Children; Glaucoma; High blood pressure; Kidney or liver diseases; Benign prostatic hypertrophy.
In addition, some of these medications may interact with some anticoagulants and central nervous system depressant remedies, such as anxiolytics or anti-depressants, so it is advisable to consult a doctor before using.
