Diphenhydramine Tablet: Uses, Dosage, Side Effects, Precautions and Alternates

Quick overview

Diphenhydramine Tablet is an antihistamine used for sneezing, runny nose, watery eyes, hives, skin rash, itching, and other cold or allergy symptoms, as well as motion sickness, certain Parkinson's disease symptoms, and to help induce sleep or treat insomnia in adults. It works by blocking histamine, a natural body chemical that causes allergic symptoms. It should be used exactly as directed, with dosing that varies by age, and it is generally avoided in older adults and in children under 2 years old.

What is Diphenhydramine Tablet

Diphenhydramine is an antihistamine that reduces the effects of a natural chemical called histamine in the body. Histamine can cause sneezing, itching, watery eyes, and runny nose. It belongs to the antihistamine drug class and is also used as an anticholinergic antiemetic, an anticholinergic antiparkinson agent, and as a sedative/hypnotic.

Diphenhydramine Tablet uses

• Sneezing, runny nose, watery eyes, hives, skin rash, itching, and other cold or allergy symptoms
• Motion sickness
• To help induce sleep
• Certain symptoms of Parkinson's disease
• Allergy and cold symptoms such as red, itchy, watery eyes and itching of the nose or throat
• Insomnia (difficulty falling asleep or staying asleep) in adults

Benefits of Diphenhydramine Tablet

• Helps relieve allergy symptoms such as sneezing, runny nose, and itching
• Helps reduce itchy, watery eyes caused by allergies
• Can relieve hives (urticaria) and skin itching
• May help prevent or treat motion sickness, including nausea and dizziness
• Some formulations are used as a short-term sleep aid because they cause drowsiness

How Diphenhydramine Tablet works

Diphenhydramine works by blocking the action of histamine, a substance in the body that causes allergic symptoms. It also affects certain areas of the brain that promote wakefulness, which is why it can cause drowsiness.

Diphenhydramine Tablet dosage

Use exactly as directed on the label or as prescribed by your doctor; do not use in larger or smaller amounts or for longer than recommended. Cold or allergy medicine is usually taken only for a short time until symptoms clear up. Do not give this medicine to a child younger than 2 years old, and always ask a doctor before giving a cough or cold medicine to a child. Do not use diphenhydramine to make a child sleepy.

For motion sickness, take it before you will be in a situation that causes motion sickness, such as a long car ride, plane, or boat trip, and continue taking it with meals and at bedtime for the rest of the trip. As a sleep aid, take it shortly before bedtime.

If you are taking the liquid form, measure the dose with a special dose-measuring spoon or medicine cup, not a household spoon. Call your doctor if your symptoms do not improve after several days of treatment, or if you have a fever with a headache, cough, or skin rash.

If you are on a regular dosing schedule and miss a dose, take it as soon as you remember, but skip it if it is almost time for your next dose; do not take extra medicine to make up for a missed dose. This medication can affect the results of allergy skin tests, so tell any doctor who treats you that you are using diphenhydramine.

Available forms and strengths

• Tablet
• Chewable tablet
• Capsule
• Liquid/oral solution
• Injection

Side effects of Diphenhydramine Tablet

Common

• Dizziness, drowsiness, loss of coordination
• Dry mouth, nose, or throat
• Constipation, upset stomach
• Dry eyes, blurred vision
• Day-time drowsiness or "hangover" feeling after night-time use
• Feeling excited or restless (especially in children)
• Muscle weakness

Serious

• Signs of an allergic reaction: hives, difficult breathing, swelling of the face, lips, tongue, or throat
• Pounding heartbeats or fluttering in the chest
• Painful or difficult urination
• Little or no urinating
• Confusion, feeling like you might pass out
• Tightness in the neck or jaw, uncontrollable movements of the tongue
• Vision problems

Warnings and precautions

• Do not give this medication to a child younger than 2 years old. Always ask a doctor before giving a cough or cold medicine to a child, because death can occur from misuse of these medicines in very young children.
• Do not use diphenhydramine to make a child sleepy.
• Older adults may be more likely to have side effects from this medicine, and generally it should not be used in older adults except to manage serious allergic reactions.
• Do not use this medicine with any other product containing diphenhydramine, even one used on the skin, and ask a doctor or pharmacist before using any other cold, cough, allergy, or sleep medicine, since antihistamines are found in many combination products.
• This medication may cause blurred vision and may impair your thinking or reactions, so be careful if you drive or do anything that requires you to be alert and able to see clearly.
• Taking this medicine with other drugs that make you sleepy or slow your breathing, such as sleeping pills, narcotic pain medicine, muscle relaxers, or medicine for anxiety, depression, or seizures, can worsen these effects.
• Tell your doctor or pharmacist if you are taking an MAO inhibitor.
• It is not known whether diphenhydramine will harm an unborn baby. Ask a doctor before using this medicine if you are pregnant.
• Diphenhydramine can pass into breast milk and may harm a nursing baby. It may also slow breast milk production. Ask a doctor before using this medicine if you are breastfeeding.
• Ask a doctor or pharmacist if it is safe for you to take diphenhydramine if you have liver or kidney disease.
• Use alcohol cautiously, as it may increase drowsiness and dizziness while taking diphenhydramine.
• Use caution driving, operating machinery, or performing other hazardous activities, since diphenhydramine may cause dizziness or drowsiness.

Storage

• Store at 20–25°C (68–77°F) at controlled room temperature.
• Keep in a cool, dry place away from excessive heat.
• Protect tablets from light and moisture.
• Keep in the original, tightly closed container until use.
• Avoid storing in bathrooms or other hot and humid areas.
• Keep out of reach and sight of children.

When to see a doctor

• Get emergency medical help if you have any signs of an allergic reaction: hives, difficulty breathing, or swelling of your face, lips, tongue, or throat.
• Stop using diphenhydramine and call your doctor right away if you have pounding or fluttering heartbeats, painful or difficult urination, little or no urinating, confusion or feeling like you might pass out, or tightness in your neck or jaw with uncontrollable tongue movements.
• If you experience vision problems or difficulty urinating or painful urination, call your doctor immediately.
• If someone has taken too much diphenhydramine, seek emergency medical attention or contact your local poison control center right away. If the person has collapsed, had a seizure, has trouble breathing, or cannot be woken up, call emergency services immediately.
• Call your doctor if your symptoms do not improve after several days of treatment, or if you have a fever with a headache, cough, or skin rash.

Alternatives

• Cetirizine
• Fexofenadine
• Levocetirizine
• Desloratadine