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Antihistamine (Oral)

Drug Class: Commonly Known As: Category:
Antihistamine (Oral) Adult, Children

Antihistamine (Oral) - What is it for

​Antihistamines are a group of medications which can be used for the following conditions : 

  • Relief of sneezing
  • Relief of watery eyes
  • Relief of runny nose (due to cold, flu or allergies)
  • Relief of itch in the eyes, nose or skin (due to insect bite or allergies)
  • Relief of redness and swelling of the skin and eyes
  • Prevention and relief of nausea
  • Relief of cough

Some antihistamines, such as chlorpheniramine, dexchlorpheniramine, tripolidine, diphenhydramine, hydroxyzine and promethazine may cause drowsiness.

Other newer antihistamines, such as cetirizine, loratadine, fexofenadine, desloratadine and levocetirizine are less likely to cause drowsiness.

While some antihistamines may be available Over-the-Counter, other antihistamines require a doctor's prescription.

Antihistamine (Oral) - Side Effects, Precautions, and Contraindications

What side effects can Antihistamine (Oral) cause?

  • Some antihistamines may cause drowsiness or dizziness
    • Avoid driving, operating machinery or other activities which require concentration while on this medication
  • Dry mouth, skin and eyes
    • Drink more water or suck an ice cube to help with mouth dryness
    • Use moisturising eye drops to resolve eye dryness
  • Difficulty in passing urine
    • Stop this medication and consult your healthcare professional for other alternatives
  • Confusion in the elderly or very young children
    • Stop this medication and consult your healthcare professional for other alternatives

If you continue to experience symptoms for more than 2 weeks even with self-treatment or have any of the following symptoms:

  • Blood in your phlegm or mucous
  • Unexplained weight loss, constant fatigue, night sweats

Your condition may be too serious for self-treatment and you should consult a doctor.

​The symptoms of a drug allergy includes one or more of the following:

  • Swollen face/eyes/lips/tongue
  • Difficulty in breathing
  • Itchy skin rashes over your whole body

If you experience, any of these symptoms, you should stop your medication and see your healthcare professionals immediately.

Before taking Antihistamine (Oral), what precautions must I follow?

  • ​Inform your healthcare professional if:
  • You are allergic to this medication or any of the other ingredients of this medication
  • You are pregnant, planning to become pregnant or breastfeeding
  • You are taking any other medications, including supplements, traditional medications and herbal remedies
  • You have difficulty urinating or have a history of other bladder conditions

What food or medicine must I avoid when I take Antihistamine (Oral)?

​If you are taking a type of medication known as monoamine oxidase inhibitors (e.g. Rasagiline), contact your healthcare professional before taking antihistamines containing chlorpheniramine or brompheniramine as your blood pressure may drop dangerously low.

Taking this medication with alcohol may worsen the drowsy side effect. Avoid all alcohol while on this medication.

Many over- the-counter medications contains antihistamines, always check with your healthcare professionals before taking two over-the-counter medications at the same time to prevent overdosing.

Antihistamine (Oral) - Dosage and How to Use

How should Antihistamine (Oral) be used?

  • ​Take this medication when necessary to relieve your symptoms
  • Different antihistamines have different maximum doses, do not exceed the maximum dose as recommended by your healthcare professional.
  • You may take this medication with or without food. However, food may slow down the absorption of antihistamines leading to a slower time to take effect. 

What should I do if I miss a dose?

​If you forget to take a dose, take it as soon as you remember. Then take your next dose at the usual time. Do not take two doses to make up for the missed dose.

What should I do if I overdose?

Antihistamine (Oral) - Handling

How should I handle Antihistamine (Oral) safely?

Antihistamine (Oral) - Storage

How should I store Antihistamine (Oral)?

Keep away from children;#Keep in a cool, dry place, away from direct sunlight;#

How should I dispose of Antihistamine (Oral) safely?

​Pack this medication into a black trash bag and seal it tightly before throwing it into the rubbish chute or bin

Antihistamine (Oral) - Additional Information

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