Alahist D is a combination antihistamine and decongestant medicine that is used to treat runny or stuffy nose, sneezing, itching, watery eyes, and sinus congestion caused by allergies, the common cold, or the flu.

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

Do not use the medicine to make a child sleepy. Misuse of this medicine may cause death in very young children.

Use exactly as directed on the label, or as prescribed by your doctor. Cold or allergy 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.

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.

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, heat, and light.

You should not use Alahist D if you are allergic to pheniramine or phenylephrine.

Do not use Alahist D 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, tranylcypromine, and others.

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

• asthma or other breathing disorder such as emphysema or chronic bronchitis;

• high blood pressure, heart disease;

• an enlarged prostate and urination problems;

• glaucoma;

• diabetes; or

• a thyroid disorder.

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

Do not give this medicine to a child younger than 6 years old without medical advice.

Since Alahist D 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.

Avoid driving or hazardous activity until you know how Alahist D 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.

Drinking alcohol can increase certain side effects of pheniramine.

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

Alahist D may cause serious side effects. Stop using Alahist D and call your doctor at once if you have:

• nervousness;

• dizziness; or

• trouble sleeping.

Common side effects of Alahist D may include:

• drowsiness;

• feeling restless or excited (especially in children);

• dry mouth, nose, or throat;

• constipation; or

• blurred vision, double vision.

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 other medicines that can cause drowsiness (such as opioid medication, sleep medicine, a muscle relaxer, or medicine for anxiety or seizures). Not all possible interactions are listed here.