Chlorpheniramine 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.

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

Histex is a combination medicine used to treat symptoms of the common cold or seasonal allergies, including sneezing, runny or stuffy nose, and itchy, watery eyes.

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

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.

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. 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 4 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.

The chewable tablet must be chewed before swallowing.

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.

If you need surgery, tell the surgeon ahead of time if you have taken a cold medicine within the past few days.

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 cause unusual results with allergy skin tests. Tell any doctor who treats you that you are taking an antihistamine.

Store at room temperature away from moisture and heat.

Do not use this medicine if you have taken an MAO inhibitor in the past 14 days. A dangerous drug interaction could occur. MAO inhibitors include isocarboxazid, linezolid, phenelzine, rasagiline, selegiline, and tranylcypromine.

You should not use this medication if you are allergic to chlorpheniramine or pseudoephedrine.

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

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

• a blockage in your stomach or intestines;

• kidney or liver disease;

• high blood pressure, heart disease, coronary artery disease, or recent heart attack;

• enlarged prostate or urination problems;

• glaucoma;

• diabetes;

• epilepsy or other seizure disorder;

• pheochromocytoma (an adrenal gland tumor);

• overactive thyroid; or

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

It is not known whether Histex will harm an unborn baby. Do not use this medicine without your doctor's advice if you are pregnant.

It is not known whether chlorpheniramine and pseudoephedrine passes into breast milk or if it could harm a nursing baby. Antihistamines and decongestants may slow breast milk production. Do not use this medicine without your doctor's advice if you are breast-feeding a baby.

Artificially sweetened liquid medicine may contain phenylalanine. Check the medication label if you have phenylketonuria (PKU).

Since cold medicine is taken as needed, you may not be on a dosing schedule. If you are taking the medication regularly, 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.

This medication may impair your thinking or reactions. Be careful if you drive or do anything that requires you to be alert.

Drinking alcohol with this medicine can cause side effects.

Ask a doctor or pharmacist before using any other cold, allergy, or sleep medicine. Many combination medicines contain chlorpheniramine or pseudoephedrine. Taking certain products together can cause you to get too much of this medicine. Check the label to see if a medicine contains an antihistamine or decongestant.

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

This medicine may cause serious side effects. Stop using this medicine and call your doctor at once if you have:

• chest pain, rapid pulse, fast or uneven heart rate;

• confusion, hallucinations, severe nervousness;

• tremor, seizure (convulsions);

• little or no urinating;

• easy bruising or bleeding, unusual weakness; or

• dangerously high blood pressure (severe headache, buzzing in your ears, anxiety, shortness of breath).

Side effects such as dry mouth, constipation, and confusion may be more likely in older adults.

Common side effects of Histex may include:

• dizziness, drowsiness, blurred vision;

• dry nose or mouth;

• nausea, stomach pain, constipation, loss of appetite;

• problems with memory or concentration; 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 Histex 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 Histex with a sleeping pill, narcotic pain medicine, muscle relaxer, or medicine for anxiety, depression, or seizures.