Chlorpheniramine is an antihistamine. Dextromethorphan is a cough suppressant. Phenylephrine is a decongestant.

Gencontuss is a combination medicine used to treat cough, runny or stuffy nose, sneezing, itching, and watery eyes caused by allergies, the common cold, or the flu.

Gencontuss will not treat a cough that is caused by smoking, asthma, or emphysema.

Gencontuss 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.

Use exactly as directed on the label, or as prescribed by your doctor. Cold or cough medicine is only for short-term use until your symptoms clear up.

Always follow directions on the medicine label about giving cough or cold medicine to a child. Do not use the medicine only to make a child sleepy. Death can occur from the misuse of cough or cold medicines in very young children.

Measure liquid medicine carefully. Use the dosing syringe provided, or use a medicine dose-measuring device (not a kitchen spoon).

Dissolve the effervescent tablets in at least 4 ounces of water. Stir and drink this mixture right away. Add a little more water to the glass, swirl gently and drink right away.

Do not take for longer than 7 days in a row. Call your doctor if your symptoms do not improve after 7 days, or if you have a fever, rash, or headaches.

If you need surgery or medical tests, tell the surgeon or doctor ahead of time if you have taken this medicine within the past few days.

Store at room temperature away from moisture and heat.

Ask a doctor or pharmacist if this medicine is safe to use if you have:

• asthma or COPD, cough with mucus;

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

• high blood pressure, heart disease;

• liver or kidney disease;

• glaucoma;

• enlarged prostate or urination problems;

• overactive thyroid; or

• pheochromocytoma (an adrenal gland tumor).

Do not use Gencontuss 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.

Ask a doctor before using this medicine if you are pregnant or breastfeeding.

Since Gencontuss is used when needed, you may not be on a dosing schedule. Skip any missed dose if it's almost time for your next dose. Do not use two doses at one time.

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

Drinking alcohol with this medicine can cause side effects.

Avoid driving or hazardous activity until you know how this medicine will affect you. Your reactions could be impaired.

Ask a doctor or pharmacist before using other cough or cold medicines that may contain similar ingredients.

Avoid becoming overheated or dehydrated during exercise and in hot weather. This medicine can decrease sweating and you may be more prone to heat stroke.

Get emergency medical help if you have signs of an allergic reaction: hives; difficult 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:

• severe anxiety, tremor, seizure (convulsions);

• fast or pounding heartbeats;

• painful or difficult urination;

• pale skin, weakness; or

• severe headache, pounding in your neck or ears.

Common side effects of Gencontuss may include:

• dizziness, drowsiness;

• blurred vision;

• dry mouth, nose, or throat;

• increased or decreased urination;

• nausea, loss of appetite, diarrhea;

• sleep problems (insomnia); or

• nervousness.

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.

Avoid using this medicine with other drugs that cause drowsiness or slow your breathing (such as opioid medicine, a muscle relaxer, or medicine for anxiety or seizures). Ask a doctor or pharmacist before using any other medication, including prescription and over-the-counter medicines, vitamins, and herbal products. Not all possible drug interactions are listed in this medication guide.