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.
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.
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 your doctor.
Try to take it at the same time each day. You may take Diphenhydramine with or without food.
This medicine is available in different oral forms such as tablet, chewable tablet, oral liquid or solution and capsule.
You may stop taking this medicine once you feel better, unless your doctor has instructed you otherwise.
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.
Alert your doctor if you have stomach ulcers or narrowing/blockage of junction between the stomach and intestine as Diphenhydramine may not be suitable for you.
Do not take this medicine if you are on your 3rd trimester of pregnancy.
Do not breastfeed while you are being treated with this medicine.
Do not give Diphenhydramine to premature or newborn babies unless instructed to do so by the doctor.
Diphenhydramine is not for use as a sleep aid for children below 16 years old.
Do not take Diphenhydramine with other similar medicines for cold and allergies, such as brompheniramine.
Inform your doctor if you have the following conditions:
- lung problems including asthma or bronchitis
- glaucoma (increased pressure in the eyes)
- prostate enlargement or bladder problems
- thyroid problems
- high blood pressure
- heart disease
- epilepsy (fits or seizures)
- myasthenia gravis (muscle weakness disorder)
- kidney disease
- liver disease
Let your doctor know if you are pregnant.
Be sure to check with your doctor or pharmacist before giving Diphenhydramine to a child or elderly. Children and elderly may be more sensitive to the side effects.
If you are going to have a urine test analysis or screening for other medicines (e.g. methadone, phencyclidine, amitriptyline) and skin testing, inform your doctor or the person who will conduct the test that you are taking this medicine.
Diphenhydramine may cause drowsiness, dizziness, blurred vision, thinking or motor skills impairment. If affected, do not drive or take part in any activity in which you need to be alert or need to see clearly.
Other side effects include any of the following: headache, tiredness, restlessness, nervousness, excitability in children, stomach discomfort, nausea, vomiting, diarrhoea, constipation, thickening of phlegm, tremors, dryness of the mouth, rashes, hives, confusion, problem concentrating, frequent or difficulty in urination, and loss of appetite.
Inform your doctor if any of these side effects do not go away or are severe, or if you experience other side effects.
Do not take Diphenhydramine with other medicines for cold and allergy e.g. brompheniramine, clemastine, hydroxyzine.
Inform your doctor and pharmacist if you are taking or using any of these medicines:
- medicines for depression e.g. amitriptyline, imipramine, isocarboxazid, phenelzine and tranylcypromine
- medicines for high blood pressure e.g. metoprolol
This list does not include all medicines that may interact with Diphenhydramine.
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.
Store in a cool, dry place away from the reach of children.
Medicines must not be used past the expiry date.