Antihistamines

The most famous and widely used antihistamines are among the second generation, which are taken daily and their effect is about 24 hours.

By neutralizing the action of histamine, antihistamine drugs relieve itching and runny nose and sneezing, and in addition to respiratory allergies, they also help relieve skin allergies.

Antihistamines should be taken before an allergy attack. Antihistamine drugs are available in different forms of tablets, eye drops, syrups and nasal sprays. .

Antihistamine drugs also cause problems. Since these drugs thicken mucous secretions, they may worsen symptoms in the case of infectious or bacterial sinusitis, so avoid using them.

Antihistamine drugs are divided into two groups: older or first generation and newer or second generation; The main difference between these two groups is the side effect of drowsiness. Antihistamines of the second generation, unlike the first generation, cause this common complication less often.

From this group, we can refer to diphenhydramine, clemastine, and chlorpheniramine. The drugs of this group may cause many side effects because they act non-specifically and have anticholinergic effects (they inhibit the effect of acetylcholine, a neurotransmitter). 

Among these side effects, we can mention: Drowsiness and problems in thinking: This complication is dangerous in that it may cause work accidents and car accidents in adults, but the available research shows that children who suffer from this Those who use drugs are less likely to suffer from this complication. Dry mouth – dizziness – anxiety – palpitations – sore throat in men with enlarged prostate. The use of these drugs may worsen problems in urination. 

To adapt to the sleep-inducing effect of these drugs, it is helpful to observe the following points: 
Take the drug at home a few hours before going to bed. 
Avoid other drugs that have a sleeping effect. 
Avoid driving and operating heavy machinery while using these drugs. 
The hypnotic effect of these drugs may decrease over time. 

Fexofenadine, Loratadine, and Cetirizine are second generation antihistamine drugs. These drugs do not have anticholinergic properties and therefore do not cause drowsiness in prescribed amounts. 
Common side effects of this group of drugs include headache, dry mouth, and dry nose, which are often temporary and resolve during treatment. In rare cases, heart palpitations and a feeling of heaviness in the chest occur while taking these drugs, in which case you should see a doctor immediately. Pregnant and lactating women should avoid these drugs unless prescribed by a doctor . .
Antihistamine Nasal Sprays 
Recently, topical antihistamine medicine in the form of nasal spray has also entered the pharmaceutical market. This medicine called Azelastin (trade name Astelin) can replace oral medicines for seasonal allergies and relieve congestion and nasal congestion and other allergy symptoms. 

If you have symptoms such as itching and watery eyes, antihistamine drops can make you feel better. These drugs prevent the increase of histamine in the body. Antihistamine eye drops are usually recommended as the first treatment for eye allergies. Antihistamine eye drops can quickly relieve eye allergy symptoms. But this relief may only be for a few hours. You may need to use the drops several times a day.