Diphenhydramine – Oral

Why do I need this medicine?

Diphenhydramine is used to relieve symptoms of cold and allergy such as runny nose, sneezing, itching of the nose or throat and itchy and watery eyes. It also helps relieve allergic skin conditions such as hives or itchy rash.


It may also be used for temporary relief of cough due to cold or throat irritation and is also effective for the prevention and treatment of nausea and vomiting, or dizziness that may occur with motion sickness.


This medicine can also help you sleep if you have difficulty sleeping.


This medicine may be used to treat other conditions as decided by your doctor.


How do I take this medicine?

Take Diphenhydramine exactly as directed by your doctor or according to the instructions on the label. Do not take more or less than instructed by the doctor.


You may take Diphenhydramine with or without food.


You may stop taking this medicine once you feel better, unless your doctor has instructed you otherwise.


What should I do if I have forgotten to take this medicine?

Take the missed dose as soon as you remember. If it is almost time for your next dose, skip the missed dose and return to your normal dosing schedule.


DO NOT double a dose under any circumstances.


When should I not use this medicine?

Do not take Diphenhydramine if you are breastfeeding.


Do not give Diphenhydramine to premature or newborn babies unless instructed to do so by the doctor.


Do not give Diphenhydramine to children below 6 years old unless instructed to do so by the doctor. Diphenhydramine is not recommended for use as a sleep aid for children below 6 years old.


What should I take note of while taking this medicine?

Inform your doctor if you have any of the following conditions:


– lung problems, such as asthma or bronchitis

– glaucoma (increased pressure in the eyes)

– stomach ulcers or narrowing/ blockage of junction between the stomach and intestine

– prostate enlargement or bladder problems

– thyroid problems

– high blood pressure

– heart disease

– epilepsy (fits or seizures)


Let your doctor know if you are pregnant.


What side effects could I experience?

Diphenhydramine may cause drowsiness, blurred vision and dizziness. If affected, do not drive or take part in any activity in which you need to be alert.


Other side effects may include any of the following: headache, tiredness, restlessness, nervousness, excitability in children, problems sleeping, stomach discomfort, nausea, thickening of phlegm, tremors and dryness of the mouth, nose and throat.


Inform your doctor if any of these side effects do not go away or are severe, or if you experience other side effects.


Can I take this with other medicines?

Inform your doctor and pharmacist if you are taking or have taken any of these medicines:


– medicines for depression e.g. amitriptyline, imipramine, fluoxetine, moclobemide, phenelzine, tranylcypromine

– medicines for high blood pressure e.g. metoprolol


Always notify your doctor and pharmacist if you are taking any other medicines, including herbal tonics such as traditional Chinese medicines, supplements and medicines that you buy without a prescription.


What special dietary instructions should I follow?

Avoid alcohol.


How should I store this medicine?

Store in a cool, dry place away from the reach of children.


Medicines must not be used past the expiry date.