Chlorpheniramine and pyrilamine are antihistamines that reduce the effects of natural chemical histamine in the body. Histamine can produce symptoms of sneezing, itching, watery eyes, and runny nose.

Phenylephrine is a decongestant that shrinks blood vessels in the nasal passages. Dilated blood vessels can cause nasal congestion (stuffy nose).

MyHist-PD is a combination medicine used to treat runny or stuffy nose, sneezing, itching, watery eyes, and sinus congestion caused by allergies, the common cold, or the flu.

MyHist-PD may also be used for purposes not listed in this medication guide.

You should not use this medicine if you have severe coronary artery disease, diabetes, an overactive thyroid, asthma, pneumonia, or other breathing problems.

Do not use this medicine if you have used an MAO inhibitor in the past 14 days, such as isocarboxazid, linezolid, methylene blue injection, phenelzine, rasagiline, selegiline, or tranylcypromine.

Do not give this medication to a child younger than 6 years old. Death can occur from the misuse of cough and cold medicines in very young children.

You should not use antihistamine medication to make a child sleepy.

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. Cough or cold medicine is usually taken only for a short time until your symptoms clear up.

Do not give this medication to a child younger than 6 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 antihistamine medication to make a child sleepy.

Do not crush, chew, or break an extended-release tablet. Swallow it whole.

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.

Shake the oral suspension (liquid) well just before you measure a dose.

Store at room temperature away from moisture, heat, and light. Do not allow liquid medicine to freeze.

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.

Do not use MyHist-PD if you have used an MAO inhibitor in the past 14 days. A dangerous drug interaction could occur. MAO inhibitors include isocarboxazid, linezolid, methylene blue injection, phenelzine, rasagiline, selegiline, tranylcypromine, and others.

You should not use this medicine if you are allergic to chlorpheniramine, phenylephrine, pyrilamine, or to other decongestants, or if you have:

• severe coronary artery disease;

• diabetes;

• overactive thyroid; or

• asthma, pneumonia, or other breathing problems.

Ask a doctor or pharmacist if it is safe for you to take this medicine if you have:

• heart disease or high blood pressure;

• blood circulation problems;

• glaucoma;

• an ulcer or obstruction in the stomach;

• enlarged prostate;

• bladder obstruction or other urination problems; or

• a history of seizures.

It is not known whether MyHist-PD will harm an unborn baby. Ask a doctor before using this medicine if you are pregnant.

Chlorpheniramine, phenylephrine, and pyrilamine can pass into breast milk and may cause side effects in the nursing baby. Antihistamines can also slow breast milk production. You should not breast-feed while using this medicine.

Take the missed dose as soon as you remember. Skip the missed dose if it is almost time for your next scheduled dose. Do not take extra medicine to make up the missed dose.

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

Overdose symptoms may include dry mouth, extreme drowsiness, confusion, ringing in your ears, tremors, seizure, dilated pupils, vomiting, and loss of consciousness.

MyHist-PD 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 with this medicine can cause side effects.

Ask a doctor or pharmacist before using any other cold, cough, allergy, or pain medicine. Many combination medicines contain antihistamines and decongestants. Taking certain products together can cause you to get too much of these medicines.

Avoid exposure to sunlight or tanning beds. This medicine can make you sunburn more easily. Wear protective clothing and use sunscreen (SPF 30 or higher) when you are outdoors.

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

MyHist-PD may cause serious side effects. Stop using MyHist-PD and call your doctor at once if you have:

• confusion, hallucinations;

• feeling nervous or irritable;

• trouble sleeping;

• little or no urination;

• a seizure (convulsions);

• numbness or tingly feeling;

• a light-headed feeling, like you might pass out;

• pounding heartbeats or fluttering in your chest; or

• increased blood pressure--severe headache, blurred vision, pounding in your neck or ears, anxiety, nosebleed.

Side effects may be more likely in older adults.

Common side effects of MyHist-PD may include:

• nausea, constipation, loss of appetite;

• rash or itching;

• increased sweating;

• dry mouth, nose, or throat;

• blurred vision;

• headache, dizziness; or

• feeling restless or excited (especially in children).

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 MyHist-PD with a sleeping pill, narcotic pain medicine, muscle relaxer, or medicine for anxiety, depression, or seizures.