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Antihistamine Uses and Side Effects

Antihistamine Uses and Side Effects

Antihistamines are considered very effective in controlling hypersensitive allergic reactions. But there are some side effects of these drugs as well.
Rashida Khilawala
Last Updated: Apr 23, 2018
Histamines are amino acids or proteins which are manufactured in the mast cell. They are responsible for triggering inflammatory responses in the brain. When the immune system observes a foreign object such as virus, bacteria or even pollen, dander, mold, etc., it starts releasing histamine. Histamine further binds with the special receptor H1 which sends signals to the brain. This triggers inflammatory response which results in swelling, inflammation, sneezing, itching, and sometimes even anaphylaxis.
People who are over-sensitive to allergens face a lot of problems as the reactions are intense and can even be fatal. To avoid or minimize the effect of histamines, antihistamines are used. Antihistamines are the chemicals which block the receptors from binding with the histamines, and by doing this they inhibit the allergic reactions.
Antihistamine are classified into two types
☛ First generation or sedating antihistamine
These antihistamines cause drowsiness. This helps the patient to sleep peacefully without any discomfort. Care must be taken after consuming the drug. Avoid activities which require full concentration such as driving, operating heavy machinery, etc., to avoid accidents.
☛ Second generation or non-sedating antihistamines
Second generation antihistamines are new drugs which cause relatively less drowsiness. This helps the person to perform his or her daily activities with ease. However, precautions need to be taken with these drugs as well. Though less, they too have sedative effects.
Antihistamine Uses
Hypersensitive reactions of any allergen can result in a life-threatening condition. To get this condition under control antihistamine drugs are taken. Following are some of the conditions in which antihistamines is used.
Hay Fever or Allergic Rhinitis
Hay fever is caused due to allergens like dust, dander, pollen, insect venom, etc., which enter the body through breathing. Common symptoms of hay fever are itchy nose, mouth and throat, runny nose, sneezing, etc. Sore throat, puffy eyes, fatigue, nasal congestion, headache may be observed in the later stage if not taken care of in time. Oral antihistamines, nasal spray, eye drops, etc. are very helpful in curing this kind of allergy.
Hives (Urticaria)
Hives are caused due to the allergic reaction of food, medicines, pollens, insect bites, etc. They can also develop due to excess exposure to sun and emotional stress. Symptoms of hives comprise red, itchy, raised patches, etc. which appear on the skin. These patches change shapes and can also spread to other parts of the body. They may disappear and after sometimes reappear. Topical antihistamine creams are the most effective treatment for this type of reaction.
Anaphylaxis
Anaphylaxis is the hypersensitive form of an allergic reaction which can cause death if not taken attended to in time. These reactions can be caused by any allergens. Most common among them are drug and food allergies. Insect bites and stings can also cause anaphylaxis. Chest tightness, difficulty in breathing, dizziness, nasal congestion, vomiting, palpitation, swelling in face, eyes and tongue, unconsciousness, anxiety, etc., are some of the symptoms of anaphylaxis. Antihistamines are used in controlling the situation, but immediate professional medical assistance is required. As soon you observe such symptoms in someone, contact emergency services immediately.
Other Uses
Apart from the conditions mentioned above, some of the other conditions in which antihistamine can be useful are common cold, drug allergies, atopic eczema, insect bite/stings, pruritus or itching, etc. Though antihistamine can be given over the counter, it is always better to consult a doctor before taking these drugs in any form.
Possible Side Effects of Antihistamine
Adequate medical guidance is vital before taking antihistamine as there are some side effects of these drugs. The most common is drowsiness and sleepiness regardless of them being sedating or non-sedating as all these drugs contain sedatives. However, the intensity and duration of these side effects may vary according to the drugs and one's resistance power. Following are some of the other side effects which may or may not be observed in all.
  • Dizziness
  • Nausea
  • Vomiting
  • Blurred vision
  • Confusion
  • Dry mouth
  • Difficulty in passing urine
  • Gastrointestinal problems
  • Disturbed sleep
  • Hyperactivity in children
Side effects are more likely to be observed in children and adults above the age of 65 years. It is very important to make sure that your health status, diet and any other medical conditions are taken into consideration before starting these medicines. People with thyroid problems, kidney, liver or heart diseases, pregnant women, breastfeeding mothers, etc., should avoid taking antihistamine without consulting a doctor.
You can get antihistamine drugs in any pharmaceutical shop. Read the label carefully as they can interact with other medications also. Avoid consumption of alcohol while taking antihistamine as it will contribute to drowsiness.
Disclaimer: This HealthHearty article is for informative purposes only, and should not be used as a replacement for expert medical advice.