Allergies Causes Treatments and Medicines mode of action of anti allergic drugs.
Allergies are a common health concern affecting millions of people worldwide, let’s understand and discuss in detail information about allergies Causes Treatments and Medicines mode of action of Anti allergic medicines. Allergy occur when the body’s immune system overreacts to a substance it perceives as harmful, triggering a range of unpleasant symptoms. Allergies can be caused by various factors, and effective treatments are available to alleviate symptoms and improve the quality of life for allergy sufferers. In this article, we will explore the different causes of allergies, available treatment options, and medications commonly used to manage allergies, including their daily doses, side effects, and contraindications.
Causes of Allergies:
Environmental Allergens:
Pollen: Pollen from trees, grasses, and weeds can trigger seasonal allergic rhinitis (hay fever).
Dust Mites: Tiny insects found in household dust can cause year-round allergies.
Mold: Mold spores present in damp areas indoors or outdoors can lead to allergy symptoms.
Pet Dander: Proteins found in the skin, saliva, or urine of pets can trigger allergies in some people.
Insect Stings: Allergic reactions to bee, wasp, hornet, or fire ant stings can be severe.
Food Allergens:
Common food allergens include peanuts, tree nuts, eggs, milk, soy, wheat, fish, and shellfish.
Allergic reaction due to Medications:
Some individuals may be allergic to certain medications, such as penicillin, aspirin, and non-steroidal anti-inflammatory drugs (NSAIDs).
Insect Allergens:
Inhaling or coming into contact with insect parts or droppings can trigger allergies.
Latex:
Allergic reactions can occur when exposed to latex, commonly found in gloves, condoms, and medical devices.
Treatment of Allergies:
The treatment of allergies aims to alleviate symptoms and prevent severe reactions. Treatment approaches include:
Allergen Avoidance:
Identifying and avoiding allergens can significantly reduce allergic reactions.
Medications for allergy:
Antihistamines: Block histamine release, reducing symptoms like sneezing and itching.
Decongestants: Provide temporary relief from nasal congestion.
Corticosteroids: Reduce inflammation and are available in nasal sprays, inhalers, or pills.
Epinephrine: Used in severe, life-threatening allergic reactions (anaphylaxis).
Immunotherapy:
Allergen immunotherapy (allergy shots or sublingual tablets) helps desensitize the immune system to specific allergens over time.
Emergency Plan for management of allergy:
People with severe allergies should have an emergency plan and carry an epinephrine auto-injector.
Medications Used to Treat Allergies:
Antihistamines:
Common examples: Cetirizine, Loratadine, Fexofenadine.
Decongestants:
Common examples: Pseudoephedrine, Phenylephrine.
Nasal Corticosteroid Sprays:
Common examples: Fluticasone, Budesonide, Mometasone.
Daily Dose: Typically once or twice daily, as prescribed by a healthcare professional.
Side Effects: Potential for nosebleeds, irritation, and throat discomfort.
Epinephrine:
Daily Dose: Only used in emergencies, administered as directed by a healthcare professional.
Side Effects: Increased heart rate, anxiety, and potential for high blood pressure.
Contraindications:
Individuals with a known hypersensitivity to a specific medication should avoid it.
Some medications may have interactions with other drugs, so it’s essential to inform your healthcare provider about all current medications.
Below is a detailed list of first-generation and second-generation anti-histaminic drugs, along with their common side effects, contraindications, and daily dosage recommendations.
First-Generation Anti-Histaminic Drugs:
Diphenhydramine :
Side Effects: Drowsiness and sedation (common). Dry mouth, nose, and throat. Blurred vision. Dizziness or lightheadedness. Gastrointestinal disturbances (nausea, constipation). Urinary retention.
Contraindications:
Hypersensitivity to diphenhydramine or related drugs. Acute asthma attacks. Glaucoma. Prostate enlargement. Severe liver or kidney disease.
Daily Dosage:
Adults: 25-50 mg every 4-6 hours, not exceeding 300 mg per day.
Children (6-12 years): 12.5-25 mg every 4-6 hours, not exceeding 150 mg per day.
Chlorpheniramine (Chlor-Trimeton):
Side Effects: Drowsiness and sedation (common). Dry mouth, nose, and throat. Blurred vision. Dizziness or lightheadedness. Gastrointestinal disturbances (nausea, constipation). Urinary retention.
Contraindications: Hypersensitivity to chlorpheniramine or related drugs. Acute asthma attacks. Glaucoma. Prostate enlargement. Severe liver or kidney disease.
Daily Dosage:
Adults: 4-8 mg every 4-6 hours, not exceeding 32 mg per day.
Children (6-12 years): 2-4 mg every 4-6 hours, not exceeding 24 mg per day.
Promethazine (Phenergan):
Side Effects:
Drowsiness and sedation (common). Dry mouth, nose, and throat. Blurred vision. Dizziness or lightheadedness. Gastrointestinal disturbances (nausea, constipation). Urinary retention.
Contraindications: Hypersensitivity to promethazine or related drugs. Children under 2 years old (due to the risk of severe respiratory depression). Comatose state. Severe liver disease.
Daily Dosage:
Adults: 25-50 mg every 4-6 hours, not exceeding 100 mg per day. Children (2-6 years): 5-10 mg every 4-6 hours, not exceeding 25 mg per day. Children (6-12 years): 10-25 mg every 4-6 hours, not exceeding 75 mg per day.
Second-Generation Anti-Histaminic Drugs:
Loratadine:
Side Effects: Headache. Dry mouth. Fatigue or drowsiness (less common than first-generation drugs).
Gastrointestinal disturbances (nausea, abdominal pain).
Contraindications:
Hypersensitivity to loratadine or related drugs. Severe liver impairment.
Daily Dosage:
Adults and children over 12 years: 10 mg once daily.
Cetirizine (Zyrtec):
Side Effects: Drowsiness and fatigue (less common than first-generation drugs). Dry mouth. Headache.
Gastrointestinal disturbances (nausea).
Contraindications:
Hypersensitivity to cetirizine or related drugs. Severe kidney impairment.
Daily Dosage:
Adults and children over 12 years: 5-10 mg once daily.
Fexofenadine (Allegra):
Side Effects: Headache. Nausea. Diarrhea. Contraindications: Hypersensitivity to fexofenadine or related drugs.
Daily Dosage:
Adults and children over 12 years: 60 mg twice daily or 180 mg once daily.
Mode of Action of Antihistamine Drugs:
Antihistamine drugs are a class of medications commonly used to treat allergies and allergic reactions. They work by blocking the action of histamine, a chemical released by the immune system during an allergic reaction. Histamine is responsible for triggering many of the symptoms associated with allergies, such as sneezing, itching, runny nose, and watery eyes.
Histamine acts on specific receptors in the body, known as histamine receptors. There are four main types of histamine receptors: H1, H2, H3, and H4. H1 receptors are the primary targets of most antihistamine drugs, as they are responsible for mediating the allergic response.
When an allergen (a substance that triggers an allergic reaction) enters the body, it stimulates the release of histamine from mast cells and basophils, which are types of immune cells. Histamine then binds to H1 receptors in various tissues, leading to the characteristic allergic symptoms.
Antihistamine drugs work by occupying and blocking the H1 receptors, preventing histamine from attaching to them. This action reduces the effects of histamine on the target tissues and helps alleviate allergic symptoms. Antihistamines are particularly effective in relieving symptoms such as sneezing, itching, and runny nose.
Older generation antihistamines, such as diphenhydramine and chlorpheniramine, have the disadvantage of causing drowsiness due to their ability to cross the blood-brain barrier and affect the central nervous system. On the other hand, newer generation antihistamines, such as loratadine, cetirizine, and fexofenadine, are less likely to cause drowsiness as they have reduced penetration into the brain.
Role of Histamine in Allergy:
Histamine is a vital chemical involved in the immune response and plays a crucial role in allergic reactions. In non-allergic individuals, histamine helps regulate various physiological processes, including stomach acid production, neurotransmission, and the sleep-wake cycle. However, in allergic individuals, histamine can trigger an exaggerated immune response.
When a person with allergies encounters an allergen (such as pollen, pet dander, dust mites, or certain foods), their immune system identifies the allergen as harmful and initiates an immune response. This response involves the activation of immune cells, including mast cells and basophils.
These immune cells release histamine in response to the allergen. Histamine, in turn, binds to its receptors, particularly H1 receptors, on various cells in the body. This binding leads to vasodilation (expansion of blood vessels), increased vascular permeability (leakage of fluids from blood vessels into surrounding tissues), and stimulation of nerve endings, causing the characteristic allergy symptoms.
Histamine’s effects on blood vessels lead to the redness and swelling seen in hives and other allergic skin reactions. It also causes nasal congestion and mucus production in the respiratory tract, leading to a runny nose and sneezing. Additionally, histamine can stimulate nerve endings, causing itching.
The severity of an allergic reaction can vary widely, ranging from mild symptoms to life-threatening anaphylaxis. Anaphylaxis is a severe allergic reaction that affects the entire body and can cause difficulty breathing, a drop in blood pressure, and loss of consciousness. Prompt medical attention is crucial in such cases.
Inference:
Allergies can significantly impact an individual’s quality of life, but with proper understanding and management, it’s possible to alleviate symptoms effectively. Identifying and avoiding allergens, coupled with the appropriate use of medications, can help allergy sufferers lead a more comfortable and symptom-free life. If you suspect you have allergies or are experiencing severe reactions, consult with a healthcare professional to receive a personalized treatment plan and prevent potential complications.