Antihistamines are a class of drugs that inhibit the activity of histamine, a substance produced by the immune system in response to allergens such as pollen, dust, or animal dander. Itching, sneezing, a runny nose, watery eyes, and inflammation are all indications of histamine. Antihistamines, which are often used to treat allergic disorders such as hay fever, hives, food allergies, and insect bites, can help relieve these symptoms. Antihistamines can also be used to treat or prevent motion sickness, nausea, sleeplessness, anxiety, and some symptoms of Parkinson's disease.
Antihistamine Subtypes
Antihistamines are classified into two types: first-generation and second-generation. First-generation antihistamines are older medications that can cross the blood-brain barrier and impact histamine receptors in the brain, spinal cord, and throughout the body. This means they can produce sleepiness, dry mouth, dizziness, low blood pressure, and a high heart rate. They can also impair driving or operating machines and interact with other medicines. Diphenhydramine, chlorpheniramine, and promethazine are examples of first-generation antihistamines.
Second-generation antihistamines are newer medications that are less likely to penetrate the blood-brain barrier and have central nervous system effects. They are more selective for histamine receptors in the peripheral nervous system and induce less side effects than first-generation antihistamines. They are also less likely to produce sedation, though some people may still feel drowsy as a result. Loratadine, cetirizine, and fexofenadine are examples of second-generation antihistamines.
Antihistamine Dosages
The dose of antihistamines is determined by the drug's kind, potency, and formulation, as well as the user's age, weight, and medical condition. Antihistamines come in a variety of formats, including tablets, capsules, liquids, syrups, sprays, drops, and creams. It is critical to adhere to the instructions on the label or prescription and not exceed the recommended dose. To avoid stomach distress, antihistamines should be taken with a full glass of water and preferably with or after food. Alcohol and other substances that can produce drowsiness or interact with antihistamines should not be combined with antihistamines. People with liver or renal disease, glaucoma, prostate enlargement, asthma, or heart disease should also use antihistamines with caution.
Antihistamines Have Side Effects
When used as indicated, antihistamines are generally safe and efficient, although they can cause some negative effects, particularly in large doses or in sensitive individuals. The following are the most prevalent antihistamine side effects:
- Sedation or drowsiness
- Dryness in the mouth, nose, or throat
- Headache
- nauseousness or vomiting
- Diarrhea or constipation
- Vision distortion
- Urination difficulties
- Perplexity or agitation
Antihistamines can cause the following rare but serious side effects:
- Allergic symptoms include redness, swelling, and difficulty breathing.
- Seizures
- Low blood pressure or a racing heart
- Psychosis or hallucinations
- Damage to the liver or kidneys
If any of these side effects occur, the user should immediately discontinue usage of the antihistamine and seek medical attention.
Conclusion
Antihistamines are valuable medications that can be used to treat a wide range of allergic and non-allergic disorders. They should, however, be used with caution and under the supervision of a doctor or pharmacist. Users should be informed of the various types, doses, and adverse effects of antihistamines and follow the directions for safe and effective use.
