Antihistamines are drugs predominantly used to relieve the ailments (symptoms) caused by allergies, such as seasonal allergic rhinitis ("hay fever"), hives, conjunctivitis and reactions to insect bites. Current knowledge does not support this. "Use of antihistamines in the treatment of asthma. Antihistamines are not indicated in the common cold. They are also used to prevent car sickness (motion sickness or motion sickness) and as a short-term cure for people suffering from insomnia." . Most antihistamines can be bought freely at drugstores, but some are only available by prescription.
For more information on the active ingredients named in the contribution or in any case belonging to this class of drugs, you can visit the website of the Italian Medicines Agency (AIFA) by clicking HERE. To search for a drug using the trade name and not the active ingredient, you can click HERE. Inside the site you can find all the package leaflets of the drugs and also some additional information. If "revoked" is written next to the drug name, the drug is no longer on the market.Types of antihistamines
Types of antihistamines
There are many types of antihistamines. Usually, they are classified into two main categories: older, so-called first generation, which can induce deep relaxation and sleepiness such as chlorphenamine, hydroxyzine and promethazine, and newer (second generation) ones such as cetirizine, loratadine and fexofenadine which do not cause such effects; second generation antihistamines have additional pharmacological properties that differ between the different molecules, and are in some cases more acceptable to patients because the number of administrations can be reduced. Both types are available. in different forms: tablets, capsules, liquids, syrups, creams, lotions, gels, drops or nasal sprays.
There are not many indications as to which type of antihistamine is most effective for reducing allergy-induced ailments (symptoms). You may need to try several before you find the one that best suits your needs. Those that do not cause drowsiness are generally the best choice. Conversely, those that induce it may be more suitable if the disorders caused by the allergy prevent sleep. Before taking antihistamines, however, it is important to consult with your family doctor or allergy specialist.How to take antihistamines
How to take antihistamines
Antihistamines, like all drugs, must be used following the doctor's instructions regarding the doses to be taken and their frequency (read the Hoax). This information can also be provided by the pharmacist or learned by reading the package leaflet, present in the box of the medicine, which contains information on dosage and possible side effects.
Before using an antihistamine it is important to:
- check if it should be taken with water and on a full stomach
- be careful to use it correctly, especially in case of nose sprays or drops
- accurately evaluate the quantity antihistamine (the dose) to be taken. It is important to remember that the dose changes with weight and age
- pay attention to the times indicated by the doctor, in some cases, you may need to take it several times a day. First generation antihistamines should be taken before bedtime
- follow the doctor's instructions regarding the duration of the treatment, some types can be used for a long time, others can only be taken for a limited time
- knowing what to do if you miss a dose or take more antihistamine (overdose) than that prescribed by your doctor
The advice also varies according to the type of antihistamine you are taking and it is therefore advisable to contact your doctor, or your pharmacist, for any doubts.Undesirable effects (side effects) of antihistamines
Undesirable effects (side effects) of antihistamines
Like all medicines, antihistamines can also cause unwanted effects (side effects).
Those determined by the first generation typology (older) may include:
- drowsiness and slower coordination of movements, of reaction and in making decisions. For this reason, after their use it is advisable not to drive or use machinery because it could be risky for one's own or others' safety.
- feeling of dry mouth (dry mouth)
- blurred vision
- difficulty emptying the bladder (urinary retention)
Side effects of second generation (newer) antihistamines can include:
- feeling of dry mouth (dry mouth)
- general feeling of being unwell
- drowsiness, although this effect is less common in newer antihistamines
In order to always have the complete list of possible undesirable effects (side effects) and, above all, specific information on situations that require medical assistance directly, it is advisable to carefully read the package leaflet supplied with the medicine. Also, if you think the drug has caused an undesirable effect, you should report it to your doctor or pharmacist.Antihistamines and other medicines, foods or alcohol
Antihistamines and other medicines, foods or alcohol
Allergic people already being treated with other medicines before taking antihistamines should consult with their doctor, or pharmacist, to avoid that the drugs interacting with each other, become less effective or cause an increase in side effects.
Some examples of medications that can cause problems when taken with antihistamines include:
- medicines for stomach ulcers or for gastroesophageal reflux diseases
- medicines for coughs and colds containing antihistamines
Food and non-alcoholic drinks, on the other hand, do not affect the activity of most antihistamines. However, it is a good idea to always follow your doctor's instructions and read the package leaflet supplied with the drug very carefully.Who can take antihistamines
Who can take antihistamines
Most people can take antihistamines but it is always advisable to consult with your doctor or pharmacist first, especially if:
- you are pregnant
- you are breastfeeding
- you are looking for an antihistamine for a child
- you are taking other medications
- you have heart, liver, kidney disease or epilepsy
How antihistamines work
Antihistamines work by counteracting the action of histamine, a chemical substance that acts in many areas of the body (skin, gastrointestinal tract, respiratory tract, heart, nervous system) by binding to different types of receptors located on the cell surface. Histamine is released by specialized cells of the body's defense system (immune system): basophils (circulating in the blood) and mast cells (present in tissues).
In people suffering from allergies, the immune system perceives as a threat harmless substances for the majority of the population such as, for example, pollen and releases histamine, thus triggering an allergic reaction (sneezing, redness and / or tearing of the eyes , swelling or redness of the skin, etc.) of varying degrees, from mild to severe, depending on individual sensitivity. This abnormal reaction of the immune system is the most frequent form of the so-called "immune-mediated"(Ie mediated by the immune system). Antihistamines, by counteracting histamine, help prevent, block or mitigate the disorders (symptoms) caused by allergic reactions.Prevention
People who already know they are allergic are generally advised to take antihistamines before coming into contact with the allergy-causing substance (called an allergen).
If, on the other hand, you suspect that you are an allergic person, it is advisable to go to your doctor and, subsequently, to the allergy specialist to undergo the necessary tests.In-depth link
NHS. Antihistamines (English)
Mayo Clinic. Antihistamine (English)