Antihistamines
On this page, your questions about using antihistamines will be answered.
What are Antihistamines?
Antihistamines are medications aimed at reducing the effects of histamine in the body. Histamine is a chemical compound released by the immune system when exposed to allergens, contributing to symptoms, such as itching, sneezing, tearing, irritation, and blood vessel dilation. Antihistamines work to reduce or prevent these allergy-related symptoms. These drugs are commonly used to treat symptoms, such as allergic rhinitis, conjunctivitis, and skin rash, in addition to being used to treat dizziness, nausea, and some sleep disorders.
What are the uses of antihistamines?
Antihistamines are used to relieve symptoms of allergies and asthma, and some types help reduce nausea caused by motion sickness. Also, they help lessen symptoms associated with inflammation and, in some cases, are used as a short-term treatment for sleep problems.
It is important to consult a specialized doctor before using antihistamines.
How effective are antihistamines, and how do they work?
Antihistamines work by reducing the effects of histamine in the body. Histamine is usually released when the body detects a harmful substance, such as an infection, leading to blood vessel dilation and skin swelling as a defensive response to protect the body.
However, in people with allergies, the immune system may mistakenly identify harmless substances, such as dust, animal dander, or house dust as threats and release histamine. This causes an allergic reaction that appears through bothersome symptoms, such as itching, watery eyes, runny or blocked nose, sneezing, and skin rash.
Antihistamines help prevent these symptoms if taken before exposure to the allergen or reduce their severity if taken after exposure.
What are the types of antihistamines?
They are available in various forms, including tablets, capsules, injections, creams, eye drops, and nasal sprays.
- There are two types of antihistamines:
- Antihistamines that may cause drowsiness include: Chlorphenamine (Piriton), Cinnarizine, Diphenhydramine, Hydroxyzine, and Promethazine.
Antihistamines that are less likely to cause drowsiness include: Acrivastine, Cetirizine, Fexofenadine, and Loratadine.
- What should you look for when buying antihistamines?
- Make sure whether the antihistamine causes drowsiness or not.
- Ensure that the antihistamine is not taken with medications that may interact or cause problems when used with antihistamines, such as:
- Some types of antidepressants.
- Medications for stomach ulcers or indigestion.
Cough and cold medicines that also contain antihistamines.
Frequently Asked Questions (FAQs)
What are the contraindications for using antihistamines?
- Absolute contraindications:
- Hypersensitivity: A known allergy to a specific antihistamine or any of its components. This can lead to severe allergic reactions.
- Acute asthma attack: Antihistamines, especially older first-generation antihistamines, can thicken bronchial secretions, which may worsen an asthma attack.
Newborns or Premature Infants: Antihistamines are generally not recommended for very young infants due to the potential for serious side effects.
- Relative contraindications (use with caution and under a doctor’s supervision):
- Pregnancy and breastfeeding: Although some antihistamines are considered safe during pregnancy and breastfeeding, it is essential to consult a doctor to assess the potential risks and benefits.
- Elderly: Older adults may be more susceptible to the side effects of antihistamines, such as drowsiness, confusion, and urinary retention.
- Angle-closure glaucoma: Antihistamines can increase eye pressure, which may worsen glaucoma.
- Enlarged prostate: Antihistamines can cause urinary retention, which may be a problem for men with an enlarged prostate.
- Cardiovascular diseases: Some antihistamines can cause rapid heart rate or palpitations, which may be concerning for individuals with heart conditions.
- Kidney or liver diseases: These conditions can affect the metabolism and excretion of antihistamines, increasing the risk of side effects.
Epilepsy: Some antihistamines may lower the seizure threshold, increasing the risk of seizures in individuals with epilepsy.
What are the side effects of antihistamines?
- Side effects of antihistamines that cause drowsiness:
- Drowsiness.
- Dry mouth.
- Blurred vision.
Difficulty urinating.
- Side effects of antihistamines that do not cause drowsiness:
- Headache.
- Nausea and vomiting.
Dry mouth.
What is the proper way to use antihistamines?
Antihistamines are usually used according to the dosage and instructions specified by the doctor or the leaflet provided with the medication.
- General guidelines for using antihistamines:
- You should follow the instructions on the medication leaflet or medical guidance, and the dosage usually varies depending on the type of medication and the patient’s age.
- It is best to take antihistamines at the scheduled time. They are often recommended in the evening if they cause drowsiness, and in the morning if they do not.
- Some antihistamines can be taken with or without food. You should check the medication’s leaflet.
- Avoid taking antihistamines with other medications that may cause negative interactions, such as antidepressants or cough medicines that also contain antihistamines.
- Avoid driving or operating heavy machinery after taking antihistamines that cause drowsiness.
