The antihistamines are medicines to treat the symptoms of allergies. There are different types of antihistamines, which are classified into different generations according to their sedative effect and chemical composition. These drugs block the histamine H1 receptors, which are responsible for allergic reactions. Antihistamines can have minor side effects, such as headaches and insomnia. It is important to follow the directions of a health care provider and read labels carefully before use.
What are antihistamines
Definition and characteristics
Antihistamines are drugs used to treat the symptoms of allergies. These drugs block histamine receptors - an inflammatory substance released by the body in the presence of an allergen - and therefore reduce histamine-induced symptoms such as allergic rhinitis, sneezing, watery and itchy eyes, itchy skin and hives. Currently, there are different types of antihistamines that are classified according to their sedative effect (causing drowsiness) and according to their chemical composition.
Role of antihistamines in the treatment of allergies
Antihistamines are used to treat the symptoms of respiratory allergies such as seasonal allergic rhinitis, asthma, which can be caused by airborne irritants such as pollen, dust mites or animal hair. They are also effective in the treatment of allergic skin reactions, such as atopic dermatitis or urticaria, which often manifest as itching and rashes. In addition, antihistamines can be used to treat nausea, vomiting, motion sickness and insomnia in some cases.
Types of antihistamines
Antihistamines are classified into two main types: first and second generation. Each type has a different chemical composition and sedative effect, and are used in different situations.
First generation
First generation antihistamines have a unique chemical composition and a strong sedative effect. These drugs can cause drowsiness, decreased concentration, dry mouth and blurred vision. In addition, first-generation antihistamines are used to treat conditions such as urticaria, dermatitis and allergic rhinitis. Examples of first-generation antihistamines include diphenhydramine, chlorpheniramine and hydroxyzine.
Second generation
Second-generation antihistamines have a different chemical composition than first-generation antihistamines and cause fewer sedative side effects. These drugs are also used to treat allergic conditions, such as allergic rhinitis and chronic urticaria. Second-generation antihistamines include loratadine, cetirizine and fexofenadine.
Differences between the different types
- First-generation antihistamines have a stronger sedative effect than second-generation antihistamines.
- First-generation antihistamines have more common side effects, such as drowsiness, dry mouth and blurred vision.
- Second-generation antihistamines have a longer duration of action than first-generation antihistamines and can be taken less frequently.
- Second-generation antihistamines are less likely to interact with other medicines than first-generation antihistamines.
In general, the type of antihistamine prescribed will depend on the patient's clinical situation, including their medical history and the nature and severity of their allergic symptoms.
Symptoms and diseases treated with antihistamines
Antihistamines are drugs used to treat different symptoms caused by allergies. Although it is true that their main function is to prevent the release of histamine in the body, which is very useful for treating respiratory allergies, they also have a number of properties that can be of great help in treating other conditions.
Respiratory allergies (allergic rhinitis, asthma)
Allergic rhinitis is a condition that occurs when our body's immune system overreacts to certain allergens, such as pollen, dust, animal hair, among others. Symptoms include frequent sneezing, itchy nose, nasal congestion and runny nose. Antihistamines that block the H1 histamine receptors can be used to treat the symptoms of allergic rhinitis, which helps to reduce inflammation and relieve symptoms. Asthma, on the other hand, is a disease that affects the airways and is characterised by shortness of breath, accompanied by coughing, chest tightness and wheezing. Antihistamines can also be useful in the treatment of asthma by reducing inflammation and mucus production in the airways, which improves the patient's breathing.
Allergic skin reactions (dermatitis, urticaria)
Dermatitis and urticaria are skin diseases caused by an allergic reaction to certain allergens. Symptoms include redness, itching, blistering and flaking. In this case, antihistamines can be particularly helpful in calming skin reactions by reducing the histamine that produces these symptoms.
Other conditions treated with antihistamines (nausea, insomnia, dizziness)
Although antihistamines are mainly used to treat allergic diseases, they also have a number of properties that may be useful in treating other conditions such as nausea, motion sickness and insomnia. In the case of nausea and motion sickness, antihistamines may be useful to reduce the feeling of dizziness and to improve the patient's balance. For insomnia, some antihistamines may have sedative properties, which may help the patient to fall asleep.
Side effects
Antihistamines are widely used to treat different types of allergies, such as seasonal allergic rhinitis and immediate hypersensitivity reactions. Although they are effective in relieving allergy symptoms, antihistamines can also have some side effects. We explain the most common and less common side effects, as well as steps you can take to reduce them.
Common side effects
The most common side effects associated with antihistamines include:
- Drowsiness: This is one of the most common side effects of antihistamines. They can make you feel tired, dizzy or groggy.
- Dry mouth: Antihistamines can also cause dry mouth, which can be uncomfortable.
- Difficulty urinating: some antihistamines can make it difficult to urinate, especially in men with prostate problems.
- Blurred vision: Antihistamines can affect vision, making it a little blurry.
- Constipation: some antihistamines can cause constipation, which can be a nuisance.
Less common side effects
In addition to the common side effects mentioned above, less common side effects of antihistamines may also occur. These include:
- Headache: some antihistamines may cause headaches in some people.
- Nausea and vomiting: In rare cases, antihistamines can cause nausea and vomiting.
- Allergic reactions: Although rare, some people may experience an allergic reaction to antihistamines. If you experience a rash, swelling or difficulty breathing, call a doctor immediately.
- Heart palpitations: some antihistamines may cause heart palpitations in some people.
- Confusion: some antihistamines may affect the ability to think clearly in some people.
Measures to reduce the side effects of antihistamines
There are several steps you can take to reduce the side effects of antihistamines:
- Read the label: Read the label carefully before taking any antihistamine. Make sure you are taking the correct dose and following all instructions.
- Talk to your doctor: If you have any concerns about the side effects of antihistamines, talk to your doctor. They can suggest other options and may be able to give you a different dose or treatment.
- Do not drive or use heavy machinery: If you feel drowsy or dizzy after taking an antihistamine, avoid driving or using heavy machinery until you feel better.
- Avoid alcohol: Alcohol can increase the drowsiness associated with antihistamines. It is best to avoid alcohol while taking these medicines.
Use and precautions
When using antihistamines, it is important to follow your doctor's instructions or the manufacturer's recommendations for dosage and duration of use. Here are some important details to keep in mind when using these drugs.
Use in adults and children
Antihistamines can be used in adults and children. However, the dose must be appropriate for the age, weight and condition being treated. Also, some antihistamines may not be safe for children under a certain age. Therefore, it is important to talk to your doctor before giving antihistamines to children.
What to do if a dose is missed or more than the recommended dose is taken
If a dose of antihistamine is missed, it should be taken as soon as possible. However, if the next dose is close, it is best to skip the missed dose and follow the usual schedule. Never take extra doses in an attempt to make up for a missed dose.
If more than the recommended dose is taken, side effects may be more serious. If you suspect that someone has taken an overdose of antihistamines, seek medical attention immediately.
Personal preferences and eligibility factors
Different people may have different preferences as to which antihistamines they prefer to use. Some may prefer first-generation antihistamines because they work faster, but others may prefer second-generation antihistamines because they do not cause drowsiness. In addition, certain medical conditions may influence the choice of antihistamines, so it is important to talk to your doctor to determine which antihistamine is most appropriate.
Precautions when mixing antihistamines with other medicines
Some medications can interact with antihistamines, which may increase side effects or decrease effectiveness. Medications that may interact with antihistamines include other allergy medications, barbiturates, benzodiazepines, certain antidepressants, certain antibiotics, and other prescription or over-the-counter medications. It is important to always inform your doctor or pharmacist of all medications you are taking to avoid potentially dangerous interactions.
Important safety and effectiveness information
It is important to note that antihistamines are not appropriate for all people or all allergies. In addition, some antihistamines can have serious side effects, especially if taken in higher doses than recommended. Antihistamines are not the only option for treating allergies and there may be risks associated with their use if they are used incorrectly. It is therefore important to always talk to your doctor before starting any new medication, and to watch out for adverse symptoms.
Alternatives to antihistamines
Other allergy medicines
There are other medications that can help in the treatment of allergies such as nasal corticosteroids, decongestants and sodium cromoglycate. Nasal corticosteroids are similar to hormones produced in the body and help reduce inflammation in the nose. Decongestants, on the other hand, help reduce swelling in the airways. Sodium cromoglycate is used to prevent the release of histamine in the body. It is important to note that these medicines can also have side effects, so it is always advisable to talk to a doctor before using any medicine.
Natural remedies and lifestyle changes
In addition to allergy medications, there are some natural remedies and lifestyle changes that can help relieve allergy symptoms. Some of these remedies include:
- Cleanliness: Keeping the house clean and dust-free and avoiding contact with known allergens can help reduce symptoms.
- Water vapour: inhaling water vapour can help relieve nasal congestion and dry coughs.
- Food: Some foods such as fish, yoghurt and onions can be beneficial for allergy due to their omega-3 fatty acid and quercetin content.
- Herbal teas: herbal teas such as chamomile and green tea can relieve nasal congestion and swelling.
- Exercise: Exercising outdoors can expose the body to allergens, but there are certain types of exercise such as yoga that can help reduce allergy symptoms.
Practical medical advice to alleviate symptoms
In addition to medicines and natural remedies, there are some practical tips that can help alleviate allergy symptoms:
- Use a humidifier: A humidifier can help reduce dryness in the throat and nose.
- Avoid smoking: Tobacco smoke can irritate the airways and worsen allergy symptoms.
- Take showers after spending time outdoors: This can remove allergens from the body and reduce allergy symptoms.
- Wear sunglasses and a face mask: this can reduce the exposure of the eyes and nose to allergens in the air when spending time outdoors.
- Rest: adequate rest can help the body recover and reduce allergy symptoms.
It is important to note that while these remedies may help relieve allergy symptoms, it is always advisable to talk to a doctor before using any natural remedies or making major lifestyle changes. In addition, if allergy symptoms are severe or do not improve with available treatments, the help of an allergy specialist may be necessary.
Eye allergies and runny nose
Eye allergies and runny nose are two very common symptoms in allergy sufferers. In some cases it all starts with nasal congestion, but patients may also experience sneezing, runny nose and itchy nose and eyes. For this reason, it is important to know which treatments are most effective in treating allergic rhinitis and allergic conjunctivitis.
Treatment of allergic rhinitis
Allergic rhinitis is inflammation of the nasal mucosa that occurs as a result of an allergic reaction. When taken regularly, antihistamines can help reduce nasal congestion and other symptoms of allergic rhinitis, such as itching, sneezing and runny nose. In addition, in some cases it may be advisable to use nasal antihistamines that are applied to the nose, but only under the supervision of a healthcare professional. In some cases, doctors recommend a combination of different medications to ensure relief of symptoms. Lifestyle measures that can help relieve the symptoms of allergic rhinitis include:
- Keep the environment clean and free of dust and other allergens.
- Use air conditioning with appropriate air filters
- Avoid using upholstery and carpets in the home.
- Keep windows closed during the pollination season.
- Using a humidifier in dry environments
Treatment for allergic conjunctivitis
Allergic conjunctivitis is an inflammation of the conjunctiva that can cause itching, redness and tearing. The most effective treatment for allergic conjunctivitis is ocular antihistamines that are applied directly to the eye. These medications can reduce swelling, itching and redness in the affected eye. It is also important for the patient to wash their hands frequently to prevent the spread of bacteria. To prevent allergic conjunctivitis, it is advisable to avoid contact with known allergens, such as dust or pollen. In addition, patients with allergic conjunctivitis should avoid rubbing their eyes, as this can worsen the symptoms.
Frequently asked questions about antihistamines
What is the best antihistamine for an allergy?
The best antihistamine for an allergy depends on many factors, such as the type of allergy, age, other medications being taken, and other health problems present. Second-generation antihistamines are generally more recommended than first-generation antihistamines because they are less sedating and are taken once a day. However, each person is different and the health care provider can suggest the most appropriate treatment for a specific case.
Is it safe to take antihistamines every day?
Yes, it is safe to take antihistamines every day if taken correctly. In fact, some second-generation antihistamines are recommended to be taken once a day for continuous control of allergy symptoms. But it is important to let the health care provider determine the correct dose and duration of treatment for each individual.
Do all antihistamines cause drowsiness?
Not all antihistamines cause drowsiness, although some may be more likely to cause this side effect. First-generation antihistamines are more associated with drowsiness than second-generation antihistamines. However, everyone is different, and some people may experience drowsiness with second-generation antihistamines. It is important to read labels carefully and talk to your health care provider to determine which antihistamine is best suited for you.
How long does it take for an antihistamine to work?
The time it takes for an antihistamine to work depends on the type of antihistamine and the dose. Some antihistamines may start working in as little as 20 minutes, while others may take several hours. Also, sometimes a daily dose needs to be taken for several days before adequate symptom control is achieved. It is important to read labels carefully and follow your health care provider's instructions to determine the right time to take antihistamines.
Can antihistamines cause allergic reactions?
Although rare, some antihistamines can cause allergic reactions. If a person has an allergic reaction when taking an antihistamine, they should seek medical attention immediately. Symptoms of an allergic reaction may include difficulty breathing, swelling of the face, tongue or throat, hives and itching.
What are the side effects of antihistamines?
The side effects of antihistamines vary depending on the type of medicine and the person taking it. The most common side effects of antihistamines are drowsiness, sedation and dizziness. Less common side effects may also be experienced, such as dry mouth, changes in appetite and vision, and problems urinating. It is important to read labels carefully and talk to your health care provider to understand the possible side effects of antihistamines.
Is it possible to take antihistamines during pregnancy or breastfeeding?
It is important to consult a healthcare provider before taking antihistamines during pregnancy or breastfeeding. Although some antihistamines are considered safe during pregnancy, others may have potential risks to the fetus or newborn. The health care provider can determine which antihistamine is most appropriate and what dose is right for an individual in these circumstances.
Is it necessary to consult a doctor before taking antihistamines?
Although antihistamines are available over-the-counter, it is important to talk to a health care provider before taking them. Antihistamines can interact with other medications and existing health problems, and the health care provider can determine the best antihistamine for the specific situation. In addition, the health care provider can help determine the appropriate dose and duration of treatment.
Can antihistamines relieve sneezing and nasal and eye itching?
Yes, antihistamines can relieve the symptoms of sneezing and itchy nose and eyes that are associated with allergies. Antihistamines block the effects of histamine, which is a substance released by the body during an allergic reaction that causes these symptoms. It is important to remember that antihistamines do not cure allergies, but only relieve the symptoms.
Conclusion Antihistamines are very useful drugs in the treatment of allergy symptoms. Blocking histamine H1 receptors reduces symptoms associated with inflammation and histamine, such as allergic rhinitis, itching and watery eyes. Different types of antihistamines are available and the choice of antihistamines will depend on the severity of symptoms, the patient's age and other factors that a doctor must assess.