Diphenhydramine
About Diphenhydramine
Diphenhydramine is an oral medication primarily used to relieve allergy symptoms, hives, runny nose, itchy eyes, and sneezing. It is also commonly used to treat temporary sleeplessness and to prevent or treat motion sickness. This medicine works quickly to provide relief from these uncomfortable symptoms.
You should take this medicine exactly as directed by your doctor or according to the package label, often on an as-needed basis when symptoms arise. It can be taken with or without food, though taking it with food or milk may help if it upsets your stomach. Making small adjustments, such as drinking plenty of fluids and using a humidifier, can also help soothe dry nasal passages while using this treatment.
While highly effective, Diphenhydramine can cause some common side effects, most notably drowsiness and dry mouth. These are typically mild and temporary, but you should contact your doctor immediately if you experience serious side effects like a very fast heartbeat, severe confusion, or difficulty urinating.
Talk to your doctor before taking this medicine if you have certain health conditions, such as breathing problems like asthma, high pressure in the eye, or thyroid issues. Do not take this if you have a blockage in your bladder, a severe stomach obstruction, or if you are currently taking certain medications for depression called MAO inhibitors.
This medicine can interact with alcohol, causing extreme sleepiness, so you should avoid drinking alcoholic beverages while using it. It also interacts with other medications that cause drowsiness, such as sleep aids or muscle relaxants. If you are pregnant, breastfeeding, or an elderly individual, consult your doctor or pharmacist before starting this treatment to ensure it is safe for you.
Uses of Diphenhydramine
Medicinal Benefits
Diphenhydramine helps relieve allergy symptoms, motion sickness, and occasional sleeplessness. The key benefits of Diphenhydramine include:
- Provides Fast Symptom Relief: Works quickly to help relieve allergy symptoms and motion sickness, allowing you to return to daily activities with less discomfort.
- Relieves Allergy Symptoms: Helps reduce sneezing, runny nose, watery eyes, and other allergy-related symptoms.
- Reduces Itching and Irritation: Helps relieve itching and skin discomfort associated with allergic reactions.
- Supports Short-Term Sleep Relief: May help you fall asleep faster when used for occasional sleeplessness, promoting restful sleep and recovery.
- Dries Excess Nasal and Eye Secretions: Helps reduce excess fluid production in the nose and eyes, supporting clearer breathing and greater comfort.
Directions for Use
Always take Diphenhydramine exactly as directed by your doctor or according to the product packaging. Do not take more than the recommended amount.
- Swallow the tablet or capsule whole with a full glass of water. Do not crush or chew it unless specified by the product packaging.
- If you are taking the liquid form, use a special medical measuring spoon or cup to measure your dose accurately. Do not use a regular household spoon, as you may not get the correct amount.
- To prevent motion sickness, take your dose 30 minutes to one hour before you start travelling.
- If using this medicine as a sleep aid, take it about 30 minutes before bedtime.
Remember to consult your doctor or pharmacist if your symptoms do not improve within a few days, or if they get worse.
Storage
Side Effects of Diphenhydramine
Common Side Effects (Usually mild)
- Drowsiness or sleepiness
- Dry mouth, nose, or throat
- Dizziness or lightheadedness
- Thickened mucus in the airways
Serious Side Effects (Consult your doctor right away)
- Difficulty urinating or inability to empty your bladder
- Fast, pounding, or irregular heartbeat
- Severe confusion, nervousness, or restlessness (especially in children)
- Signs of a serious allergic reaction, such as a severe skin rash, itching, swelling of the face, tongue, or throat, or severe trouble breathing
Medicines Containing this Salt
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Drug Warnings
- Check other medicine labels: Always read the labels of other over-the-counter cough, cold, or allergy products. Many contain the same active antihistamine ingredient, and combining them can lead to an accidental and dangerous overdose.
- Use the correct measuring tool: Never use standard kitchen spoons for liquid doses. Always use the syringe, dropper, or medicine cup that came with the product to ensure accurate dosing.
- Be cautious with elderly patients: Older adults are more sensitive to the side effects of this medicine, particularly dizziness, drowsiness, confusion, and low blood pressure, which can increase the risk of falls.
- Avoid prolonged use for sleep: This medicine is only meant for short-term relief of occasional sleeplessness. Using it as a sleep aid for more than two weeks can lead to your body building a tolerance, making it less effective.
- Watch for excitement in children: While this medicine typically causes drowsiness, it can sometimes cause the opposite effect in children, making them unusually excited, restless, or hyperactive.
Drug Interactions
Drug-Drug Interactions
Inform your doctor if you are taking any of the following medicines, as they may interact with Diphenhydramine:
- MAO inhibitors (for depression): Taking these with Diphenhydramine can prolong and intensify its drying and sedative effects.
- Other central nervous system depressants: Medicines like anxiety drugs, sedatives, muscle relaxants, or narcotic pain relievers can cause severe drowsiness and slow breathing when taken together.
- Other anticholinergic medicines: Combining this medicine with drugs for overactive bladder or Parkinson's disease can increase the risk of severe dry mouth, constipation, and difficulty urinating.
Drug-Food Interactions
Certain foods and beverages may affect how Diphenhydramine works or increase the risk of side effects. Examples include:
- Alcohol: Consuming alcohol while taking this medicine can severely increase drowsiness, dizziness, and mental confusion, making activities like driving highly dangerous.
Drug-Disease Interactions
Inform your doctor if you have a history of the following conditions before taking Diphenhydramine, as it may worsen your condition or require additional monitoring:
- Glaucoma (narrow-angle): This medicine can increase pressure inside the eye, which may worsen this condition.
- Enlarged prostate or urinary retention: It can make it even harder to urinate, leading to severe bladder discomfort.
- Asthma or chronic bronchitis: The drying effect of this medicine can thicken mucus in your lungs, making it harder to breathe during a flare-up.
Drug-Drug Interactions Checker List:
Safety Advice
Alcohol
unsafeWhen combined with alcohol, diphenhydramine can induce deep sleep. You will be unable to breathe normally and may have difficulties waking up.
Pregnancy
cautionPlease consult the doctor. Diphenhydramine should be used in pregnant women only if clinically needed, and the benefits outweigh the risks. Only consume Diphenhydramine if a doctor prescribes you.
Breast Feeding
cautionLet your doctor know if you are a nursing mother before taking Diphenhydramine; your doctor will decide whether Diphenhydramine can be taken by breastfeeding mothers or not. Only consume Diphenhydramine if a doctor prescribes you.
Driving
cautionDiphenhydramine may affect driving as it causes dizziness and feeling sleepy. So, do not drive or operate machinery or tools if this happens to you.
Liver
cautionTell your doctor before receiving the Diphenhydramine if you have a history of liver diseases/conditions. Your doctor will weigh the benefits and potential risks before prescribing Diphenhydramine.
Kidney
safe if prescribedTell your doctor before receiving the Diphenhydramine if you have a history of kidney diseases/conditions. Your doctor will weigh the benefits and potential risks before prescribing Diphenhydramine.
Children
safe if prescribedGenerally, Diphenhydramine is not recommended for children below 16 years of age without a doctor's consent. If it has to be given, then the dose must be adjusted and recommended by a child specialist only.
Habit Forming
Diet & Lifestyle Advise
- Stay hydrated: Drink plenty of water throughout the day to help ease dry mouth, throat, and nasal passages caused by this medicine.
- Suck on sugarless lozenges: If dry mouth becomes bothersome, sucking on sugar-free hard candies or chewing sugarless gum can help stimulate saliva flow.
- Avoid alcohol: Do not consume beer, wine, or spirits while taking this medicine, as alcohol can dangerously increase drowsiness and dizziness.
- Limit high-hazard tasks: Avoid driving, operating heavy machinery, or performing tasks that require sharp mental focus until you know how this medicine affects you.
- Increase dietary fibre: Since this medicine can sometimes cause constipation, eating fibre-rich foods like fruits, vegetables, and whole grains can help keep your digestion regular.
Special Advise
It is advised to avoid contact with known allergens (allergy-causing agents) such as pollen, dust, etc. Certain food items are known to cause allergies to you.
Patients Concern
Disease/Condition Glossary
Allergy: Allergy is an immune system response to foreign elements typically not harmful to your body. These foreign elements are known as ‘allergens.’ Allergic condition varies from person to person. Some might be allergic to certain foods and seasonal allergies like hay fever. At the same time, others might be allergic to pollen or pet dander. One of the symptoms of allergy is cough. Coughing occurs as a reflex action in the throat when mucus or any other foreign irritant is in it.
FAQs
Diphenhydramine is used to treat sneezing, running nose, itches, common cold symptoms, and cough.
Diphenhydramine blocks a natural substance (histamine) during an allergic reaction. Besides this, drying effects of Diphenhydramine on allergic symptoms (like watery eyes and runny nose) are caused by blocking another natural substance (acetylcholine). Together it helps relieve allergy symptoms like sneezing, running nose, watery eyes, itching, swelling, congestion, or stiffness.
Usually, Diphenhydramine is prescribed for a short term treatment (up to 2 weeks) as an anti-allergy or sleep disturbance medication. However, taking it on your own for a long time without a doctor's consent can be fatal.
If you forget to take a dose of Diphenhydramine, take the missed dose as soon as you remember it. However, if it is almost time for the next dose, skip the missed dose and continue your regular dosing schedule. Do not take a double dose to make up for a missed one.
No, it would be best if you did not stop taking Diphenhydramine abruptly as it may worsen your condition. Please consult your doctor if you are feeling better for the best advice.
Do not take Diphenhydramine if you have breathing problems like asthma, COPD or chronic bronchitis, or vision problems like glaucoma or difficulty in peeing due to enlarged prostate gland. Besides this, if you are taking alcohol, any sleeping pills or antianxiety pills immediately stop taking Diphenhydramine as it might induce drowsiness and dizziness.
You should not take other medicines along with Diphenhydramine without consulting your doctor. Inform your doctor about all other medications you are currently taking before starting Diphenhydramine as some medicines may interact with Diphenhydramine and increase the risk of side effects.
You are recommended to avoid driving after taking Diphenhydramine if it affects you. Diphenhydramine can cause dizziness, sleepiness, blurred vision, and coordination imbalance as a side effects, which can decreases your ability to drive safely. Therefore, it is best to avoid driving or operating heavy machinery until you know how Diphenhydramine affects you.
Take Diphenhydramine with or without food or as advised by your doctor. Do not exceed recommended dose.
Avoid alcohol as it can increase the side effects like drowsiness and also avoid caffeine or other stimulants, as they can interfere with the sedative effects of the Diphenhydramine.
The common side effects of Diphenhydramine are, dizziness, drowsiness, loss of coordination, dry mouth, constipation, dry eyes and blurred vision. If any of these side effects persist or worsen, please consult your doctor.
No, you should not take it every night. It is only meant for short-term, occasional sleeplessness. If you use it regularly, your body can quickly build a tolerance, meaning it will stop working as well. If your sleep problems last for more than two weeks, talk to your doctor.
Yes, drowsiness is one of the most common side effects of this medicine. Because of this, you should avoid driving, operating machinery, or performing any hazardous tasks after taking a dose until you know exactly how it affects you. Talk to your doctor if you need a non-drowsy allergy alternative.
It depends on the child's age and the specific product. You should never give this medicine to children under 2 years of age, and some oral products should not be given to children under 6 or 12 years without a doctor's advice. Always check the package label carefully and talk to your doctor or pharmacist before giving this medicine to a child.
While this medicine does not directly raise blood pressure in most people, some multi-symptom cold products containing it may also contain decongestants that can elevate blood pressure. If you have high blood pressure or heart disease, talk to your doctor or pharmacist to choose a safe formulation.
You should avoid taking it with other antihistamines, including those applied to the skin (like antihistamine creams). Doing so increases your risk of severe side effects like extreme drowsiness, dry mouth, and confusion. Talk to your doctor or pharmacist before combining any allergy medications.
When taken orally, this medicine usually begins working within 15 to 30 minutes. Its peak effects are typically felt within 1 to 2 hours, and its soothing actions generally last for about 4 to 6 hours. Talk to your doctor if your symptoms do not improve.
You should consult your healthcare provider before using this medicine if you are pregnant or breastfeeding. It can pass into breast milk and may cause drowsiness or unusual excitement in a nursing infant, and it may also reduce breast milk production. Talk to your doctor to discuss safer alternatives.
Dry mouth is a common effect of this medicine. You can manage this by drinking plenty of water, sucking on ice chips, or chewing sugar-free gum. If the dryness is severe, painful, or does not go away after you stop using the medicine, talk to your doctor.
