Antihistamines are medications used to relieve symptoms of allergic reactions by blocking the effects of histamine, a substance in the body that is released during allergic reactions. Histamine plays a central role in allergy symptoms such as itching, sneezing, runny nose, eye irritation and skin rashes. Antihistamines are often used to treat hay fever (allergic rhinitis), urticaria (hives), conjunctivitis (inflammation of the eyes), and in some cases, eczema and asthma.
Classes of antihistamines
Antihistamines are divided into two main classes:
- First generation (sedating) : These older antihistamines may cause drowsiness and impair responsiveness. Examples include diphenhydramine (Benadryl) and chlorpheniramine. Not only do they work against histamine, but they can also affect other receptors in the body, which can lead to side effects such as dry mouth, blurred vision and urinary retention.
- Second generation (non-sedating) : These newer antihistamines are more specific to histamine receptors and typically do not cause drowsiness. Examples include cetirizine (Zyrtec), loratadine (Claritin), and fexofenadine (Allegra). They are suitable for everyday use and have less impact on responsiveness.
application areas
- Allergic rhinitis : Both generations of antihistamines can be used to relieve sneezing, runny or stuffy nose, and nasal itching.
- Conjunctivitis : Antihistamines relieve itching, redness, and swelling of the eyes.
- Urticaria and angioedema : They can reduce itching and swelling of the skin.
- Insect stings and bites : To relieve itching and swelling.
- Mild allergic skin reactions : To reduce itching and rashes.
Side effects
While second-generation antihistamines are less likely to cause side effects, some people may still experience mild side effects such as headache, dry mouth, dizziness, and gastrointestinal distress. First-generation antihistamines can cause more severe side effects such as drowsiness and impaired responsiveness, which should be particularly important when driving or operating machines.
Important to note
- Antihistamines can interact with other medications, which is why it is important to consult a doctor or pharmacist before taking them with other medications.
- Pregnant or breastfeeding women should only take antihistamines after consulting a doctor.
- Specific dosages and formulations are available for children and should be taken under the guidance of a doctor.
Antihistamines are an effective way to relieve allergy symptoms, but as with all medications, it is important to read the instructions on the package insert and seek medical advice if you have any concerns.
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