Diphenhydramine

What is this medication for?

Diphenhydramine belongs to a group of medicines known as antihistamines, which helps to reduce nasal secretions and sneezing.

Diphenhydramine cough syrup also contains Ammonium chloride. This ingredient is an expectorant that helps loosen the phlegm, hence making it easier to cough up the phlegm.

It is used for:

• Cough with phlegm (wet or productive cough)
• Relief of sneezing and runny nose 

Diphenhydramine tablets may also be given to help with sleep for short periods. 

Diphenhydramine may be used for other conditions. Check with your healthcare professional if you are unsure why you are given this medication.

You can also find out about this medication by watching these videos:
They are available in English, 中文, Melayu and தமிழ்: Antihistamines(oral)

How should I take or use this medication?

• You may take this medication with or without food.
• Take this medication when necessary to relieve your symptoms
  • If you are taking this medication to help with sleep, take it half an hour before going to bed or after going to bed if you cannot fall asleep
• Do not exceed the maximum dose as recommended by your healthcare professional

What should I do if I forget to take or use this medication?

• As the medicine is to be taken only on an “as-needed” basis; there is no need to take the medication if you are not experiencing any symptoms.
• If you miss a dose, take it as soon as you remember. However, if it is almost time for your next dose, skip the missed dose and continue normally. Do not take two doses or extra medication to make up for the missed dose. 

What precautions should I take when taking or using this medication?

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 or have ever had:
  • Liver or kidney disease
  • Increased eye pressure (glaucoma)
  • Difficulty urinating or have a history of other bladder conditions
  • Seizures
  • Abnormal heart rhythm
  • Porphyria, which is a condition involving a group of disorders that affect the skin or nervous system

What are some common side effects of this medication? ​

• Drowsiness
  • Avoid driving or taking part in activities that require concentration while on this medication
• Dry mouth
  • Sip water regularly, suck an ice cube or sugar-free hard candies to help with mouth dryness
• Nausea and vomiting 

Most of these side-effects are temporary and will improve with time. Speak with your healthcare professionals if any of them continues, worsens, or affects your daily life.

What are some rare but serious side-effects that I need to seek medical advice immediately? 

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

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

You can also find out about drug allergies by watching these videos:
They are available in English, 中文, Melayu and தமிழ்: Drug Allergies

Rarely, this medication may cause:

• Dizziness
• Confusion
• Convulsions (fits)
• Fast heartbeat
• Breathing difficulties

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

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.

What food or medication should I avoid when I take or use this medication?

• Avoid alcohol as it may increase drowsiness.
• Avoid taking medications that cause drowsiness as this medication may increase the drowsy effects.
• Do not take with or within 14 days of stopping monoamine oxidase inhibitors (MAOIs) such as moclobemide or selegiline.
• Many over-the-counter medications contain antihistamines, always check with your health care professional before taking two over-the-counter medications at the same time to prevent overdosing.

How should I store this medication?

Store in a cool and dry place below 30°C, away from direct sunlight. Keep this medication away from children.

How do I throw away this medication safely? ​

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