Benadryl is an antihistamine that reduces the effects of natural chemical histamine in the body. Histamine can produce symptoms of sneezing, itching, watery eyes, and runny nose.

Benadryl is used to treat sneezing, runny nose, watery eyes, hives, skin rash, itching, and other cold or allergy symptoms.

Benadryl is also used to treat motion sickness, to induce sleep, and to treat certain symptoms of Parkinson's disease.

You should not use Benadryl to make a child sleepy.

When taking Benadryl, use caution driving, operating machinery, or performing other hazardous activities. Diphenhydramine may cause dizziness or drowsiness. If you experience dizziness or drowsiness, avoid these activities.

Use alcohol cautiously. Alcohol may increase drowsiness and dizziness while taking Benadryl.

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. Death can occur from the misuse of cough and cold medicines in very young children.

Use Benadryl 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 your symptoms clear up.

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. Death can occur from the misuse of cough and cold medicines in very young children.

You should not use Benadryl to make a child sleepy.

Measure liquid medicine with the dosing syringe provided, or with a special dose-measuring spoon or medicine cup. If you do not have a dose-measuring device, ask your pharmacist for one.

For motion sickness, take Benadryl 30 minutes before you will be in a situation that causes you motion sickness (such as a long car ride, airplane or boat travel, amusement park rides, etc). Continue taking Benadryl with meals and at bedtime for the rest of the time you will be in a motion-sickness situation.

As a sleep aid, take Benadryl within 30 minutes before bedtime.

Call your doctor if your symptoms do not improve after 7 days of treatment, or if you have a fever with a headache, cough, or skin rash.

This medication can affect the results of allergy skin tests. Tell any doctor who treats you that you are using Benadryl.

Store at room temperature away from moisture and heat.

You should not use Benadryl if you are allergic to diphenhydramine.

Ask a doctor or pharmacist if it is safe for you to take this medicine if you have other medical conditions, especially:

• blockage in your digestive tract (stomach or intestines);

• bladder obstruction or other urination problems;

• a colostomy or ileostomy;

• liver or kidney disease;

• asthma, chronic obstructive pulmonary disease (COPD), or other breathing disorder;

• cough with mucus, or cough caused by smoking, emphysema, or chronic bronchitis;

• heart disease, low blood pressure;

• glaucoma;

• a thyroid disorder; or

• if you take potassium (Cytra, Epiklor, K-Lyte, K-Phos, Kaon, Klor-Con, Polycitra, Urocit-K).

It is not known whether Benadryl 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. Antihistamines may also slow breast milk production. Ask a doctor before using this medicine if you are breast-feeding.

Older adults may be more likely to have side effects from this medicine.

Since Benadryl is used when needed, you may not be on a dosing schedule. If you are on a schedule, use the missed dose as soon as you remember. Skip the missed dose if it is almost time for your next scheduled dose. Do not use extra medicine to make up the missed dose.

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.

Benadryl may cause blurred vision and may impair your thinking or reactions. Be careful if you drive or do anything that requires you to be alert and able to see clearly.

Drinking alcohol can increase certain side effects of diphenhydramine.

Ask a doctor or pharmacist before using any other cold, cough, allergy, or sleep medicine. Antihistamines are contained in many combination medicines. Taking certain products together can cause you to get too much of this type of medicine. Check the label to see if a medicine contains an antihistamine.

Get emergency medical help if you have signs of an allergic reaction to Benadryl: hives; difficult breathing; swelling of your face, lips, tongue, or throat.

Stop using Benadryl and call your doctor at once if you have:

• pounding heartbeats or fluttering in your chest;

• painful or difficult urination;

• little or no urinating;

• confusion, feeling like you might pass out; or

• tightness in your neck or jaw, uncontrollable movements of your tongue.

Common Benadryl side effects may include:

• dizziness, drowsiness, loss of coordination;

• dry mouth, nose, or throat;

• constipation, upset stomach;

• dry eyes, blurred vision; or

• day-time drowsiness or "hangover" feeling after night-time use.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

Ask a doctor or pharmacist before using this medicine if you are also using any other drugs, including prescription and over-the-counter medicines, vitamins, and herbal products. Some medicines can cause unwanted or dangerous effects when used together. Not all possible interactions are listed in this medication guide.

Taking this medicine with other drugs that make you sleepy or slow your breathing can worsen these effects. Ask your doctor before taking Benadryl with a sleeping pill, narcotic pain medicine, muscle relaxer, or medicine for anxiety, depression, or seizures.

Benadryl is absorbed quickly in the body. You’ll probably notice the effects within about 20 to 30 minutes.

The medicine should continue to work for about four to six hours.

You should only take Benadryl for a short amount of time, unless your doctor tells you to take it for longer. If you use Benadryl for two weeks or longer, your body can start to become dependent on it.

Your dosage will depend on your medical condition, age, and other factors.

A typical dosage for adults and children ages 12 and older is one to two tablets every four to six hours.

Benadryl is sometimes used “off-label” for conditions it’s not approved to treat. For example, some research has shown the medicine may help obsessive compulsive disorder (OCD) and general anxiety.

Don’t use Benadryl for a medical condition it’s not intended to treat, unless your doctor tells you to do so.