Close look on antihistamines

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Antihistamines are drugs often given to alleviate the symptoms of allergies such as conjunctivitis, hay fever, hives and reactions to insect stings or bites. These drugs are often given to prevent motion sickness and as a brief treatment for sleeping difficulties.

What are the types?

There are different types of antihistamines and generally categorized into 2 groups:

  • Older antihistamines – can cause sleepiness such as chlorphenamine, promethazine and hydroxyzine
  • Newer antihistamines – these are less likely to cause sleepiness such as loratadine, cetirizine and fexofenadine

These drugs are also available in various forms such as capsules, tablets, syrups, liquids, lotions, creams, gels, nasal sprays and eye drops.

How to use the drug

antihistamines
Antihistamines are drugs often given to alleviate the symptoms of allergies such as conjunctivitis, hay fever, hives and reactions to insect stings or bites.

Antihistamines must be taken as instructed by the doctor or based on the instructions on the leaflet or packaging.

Before using one, it is vital to be familiar with the following:

  • How to use it – whether it needs to be taken together with water or food or how to correctly use one if as a nasal spray or eye drop
  • Dosage – this varies depending on certain factors such as the weight and age
  • When to take it – the number of times it is taken and time to use it
  • How long to use it – some types can be used for an extended period, but some are suggested for only a few days
  • What to do if a dose is missed or if too much is used

What are the possible side effects?

Antihistamines can trigger side effects similar with other drugs.

Older antihistamines

  • Dry mouth
  • Sleepiness or drowsiness and diminished coordination, judgement and reaction speed
  • Blurry vision
  • Difficulty emptying the bladder

Non-drowsy antihistamines

  • Dry mouth
  • Headache
  • Feeling sick
  • Drowsiness

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