Diphenhydramine 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.

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

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

Diphenhydramine may also be used for purposes not listed in this medication guide.

When taking diphenhydramine, 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 diphenhydramine.

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 diphenhydramine to make a child sleepy.

Diphenhydramine comes as a tablet, a rapidly disintegrating (dissolving) tablet, a capsule, a liquid-filled capsule, a dissolving strip, powder, and a liquid to take by mouth. When diphenhydramine is used for the relief of allergies, cold, and cough symptoms, it is usually taken every 4 to 6 hours. When diphenhydramine is used to treat motion sickness, it is usually taken 30 minutes before departure and, if needed, before meals and at bedtime. When diphenhydramine is used to treat insomnia it is taken at bedtime (30 minutes before planned sleep). When diphenhydramine is used to treat abnormal movements, it is usually taken three times a day at first and then taken 4 times a day. Follow the directions on the package or on your prescription label carefully, and ask your doctor or pharmacist to explain any part you do not understand. Take diphenhydramine exactly as directed. Do not take more or less of it or take it more often than prescribed by your doctor or directed on the label.

Diphenhydramine comes alone and in combination with pain relievers, fever reducers, and decongestants. Ask your doctor or pharmacist for advice on which product is best for your symptoms. Check nonprescription cough and cold product labels carefully before using two or more products at the same time. These products may contain the same active ingredient(s) and taking them together could cause you to receive an overdose. This is especially important if you will be giving cough and cold medications to a child.

Nonprescription cough and cold combination products, including products that contain diphenhydramine, can cause serious side effects or death in young children. Do not give these products to children younger than 4 years of age. If you give these products to children 4 to 11 years of age, use caution and follow the package directions carefully.

If you are giving diphenhydramine or a combination product that contains diphenhydramine to a child, read the package label carefully to be sure that it is the right product for a child of that age. Do not give diphenhydramine products that are made for adults to children.

Before you give a diphenhydramine product to a child, check the package label to find out how much medication the child should receive. Give the dose that matches the child's age on the chart. Ask the child's doctor if you don't know how much medication to give the child.

If you are taking the liquid, do not use a household spoon to measure your dose. Use the measuring spoon or cup that came with the medication or use a spoon made especially for measuring medication.

If you are taking the dissolving strips, place the strips on your tongue one at a time and swallow after they melt.

If you are taking the rapidly dissolving tablets, place a tablet on your tongue and close your mouth. The tablet will quickly dissolve and can be swallowed with or without water.

If you are taking the capsules, swallow them whole. Do not try to break the capsules.

Use diphenhydramine 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 diphenhydramine 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 diphenhydramine to make a child sleepy.

Measure liquid medicine 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 diphenhydramine 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 diphenhydramine with meals and at bedtime for the rest of the time you will be in a motion-sickness situation.

As a sleep aid, take diphenhydramine 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 diphenhydramine.

Store at room temperature away from moisture and heat.

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

Ask a doctor or pharmacist if it is safe for you to take diphenhydramine 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 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. 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 diphenhydramine 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.

Keep this medication in the container it came in, tightly closed, and out of reach of children. Store it at room temperature and away from excess heat and moisture (not in the bathroom).

It is important to keep all medication out of sight and reach of children as many containers (such as weekly pill minders and those for eye drops, creams, patches, and inhalers) are not child-resistant and young children can open them easily. To protect young children from poisoning, always lock safety caps and immediately place the medication in a safe location – one that is up and away and out of their sight and reach. http://www.upandaway.org

Unneeded medications should be disposed of in special ways to ensure that pets, children, and other people cannot consume them. However, you should not flush this medication down the toilet. Instead, the best way to dispose of your medication is through a medicine take-back program. Talk to your pharmacist or contact your local garbage/recycling department to learn about take-back programs in your community. See the FDA's Safe Disposal of Medicines website (http://goo.gl/c4Rm4p) for more information if you do not have access to a take-back program.

Unless your doctor tells you otherwise, continue your normal diet.

This medication 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 any signs of an allergic reaction to diphenhydramine: hives; difficult breathing; swelling of your face, lips, tongue, or throat.

Stop using diphenhydramine 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 diphenhydramine 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 diphenhydramine with a sleeping pill, narcotic pain medicine, muscle relaxer, or medicine for anxiety, depression, or seizures.

Ask your pharmacist any questions you have about diphenhydramine.

It is important for you to keep a written list of all of the prescription and nonprescription (over-the-counter) medicines you are taking, as well as any products such as vitamins, minerals, or other dietary supplements. You should bring this list with you each time you visit a doctor or if you are admitted to a hospital. It is also important information to carry with you in case of emergencies.

• Advil PM® (containing Diphenhydramine, Ibuprofen)
• Alahist LQ® (containing Diphenhydramine, Phenylephrine)
• Aldex CT® (containing Diphenhydramine, Phenylephrine)
• Aleve PM® (containing Diphenhydramine, Naproxen)
• Anacin P.M. Aspirin Free® (containing Acetaminophen, Diphenhydramine)
• Bayer Aspirin PM® (containing Aspirin, Diphenhydramine)
• Benadryl-D Allergy Plus Sinus® (containing Diphenhydramine, Phenylephrine)
• Children's Dimetapp Nighttime Cold and Congestion® (containing Diphenhydramine, Phenylephrine)
• Doans PM® (containing Diphenhydramine, Magnesium Salicylate)
• Endal HD® (containing Diphenhydramine, Phenylephrine)
• Excedrin PM® (containing Acetaminophen, Diphenhydramine)
• Goody's PM® (containing Acetaminophen, Diphenhydramine)
• Legatrin PM® (containing Acetaminophen, Diphenhydramine)
• Masophen PM® (containing Acetaminophen, Diphenhydramine)
• Midol PM® (containing Acetaminophen, Diphenhydramine)
• Motrin PM® (containing Diphenhydramine, Ibuprofen)
• PediaCare Children's Allergy and Cold® (containing Diphenhydramine, Phenylephrine)
• Robitussin Night Time Cough and Cold® (containing Diphenhydramine, Phenylephrine)
• Sudafed PE Day/Night Cold® (containing Acetaminophen, Dextromethorphan, Diphenhydramine, Guaifenesin, Phenylephrine)
• Sudafed PE Day/Night Congestion® (containing Diphenhydramine, Phenylephrine)
• Sudafed PE Severe Cold® (containing Acetaminophen, Diphenhydramine, Phenylephrine)
• Tekral® (containing Diphenhydramine, Pseudoephedrine)
• Theraflu Nighttime Severe Cold and Cough® (containing Acetaminophen, Diphenhydramine, Phenylephrine)
• Triaminic Night Time Cold and Cough® (containing Diphenhydramine, Phenylephrine)
• Tylenol Allergy Multi-Symptom Nighttime® (containing Acetaminophen, Diphenhydramine, Phenylephrine)
• Tylenol Severe Allergy® (containing Acetaminophen, Diphenhydramine)
• Unisom with Pain Relief® (containing Acetaminophen, Diphenhydramine)