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NoHist-A

Generic name: chlorpheniramine, phenylephrine, and phenyltoloxamine

Brand names: Nalex-A, Chlorex A, NoHist-A, West-Decon M

Used for nasal congestion
Last updated November 3, 2026 0 views
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What is NoHist-A?

Chlorpheniramine and phenyltoloxamine are antihistamines that lessen the effects of a natural chemical called histamine in the body. Histamine can cause symptoms like sneezing, itching, watery eyes, and a runny nose.

Phenylephrine is a decongestant that narrows blood vessels in the nasal passages. When blood vessels are dilated, it can lead to nasal congestion (a stuffy nose).

NoHist-A is a combination medicine that helps treat cough, runny or stuffy nose, sneezing, itching, and watery eyes due to allergies, the common cold, or the flu.

NoHist-A will not treat a cough caused by smoking, asthma, or emphysema.

NoHist-A may also be used for other reasons not mentioned in this medication guide.

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How should I take NoHist-A?

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 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.

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

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.

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.

Do not take for longer than 7 days in a row. Talk with your doctor if your symptoms do not improve after 7 days of treatment, or if you have a fever with a headache or skin rash.

Store at room temperature away from moisture and heat.

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Warnings

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, methylene blue injection, phenelzine, rasagiline, selegiline, and tranylcypromine.

This section was rewritten for readability and reviewed for meaning.

Before taking this medicine

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, methylene blue injection, phenelzine, rasagiline, selegiline, and tranylcypromine.

To make sure this medicine is safe for you, tell your doctor if you have:

  • a blockage in your digestive tract (stomach or intestines);
  • high blood pressure, heart disease, coronary artery disease;
  • glaucoma;
  • liver or kidney disease;
  • asthma or COPD, cough with mucus, or cough caused by smoking, emphysema, or chronic bronchitis;
  • bladder obstruction or other urination problems;
  • pheochromocytoma (an adrenal gland tumor);
  • overactive thyroid; or
  • if you take potassium (Cytra, Epiklor, K-Lyte, K-Phos, Kaon, Klor-Con, Polycitra, Urocit-K).

FDA pregnancy category C. It is not known whether NoHist-A will harm an unborn baby. Tell your doctor if you are pregnant or plan to become pregnant while using this medication.

This medicine can pass into breast milk and may harm a nursing baby. Antihistamines and decongestants may also slow breast milk production. Tell your doctor if you are breast-feeding a baby.

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Side Effects

Get emergency medical help if you have any of these 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 right away if you have:

  • fast or uneven heart rate;
  • pounding heartbeats or fluttering in your chest;
  • painful or difficult urination, little or no urinating;
  • tremors, seizure (convulsions); or
  • vision changes, severe dizziness, feeling like you might pass out.

Common side effects of NoHist-A may include:

  • headache, dizziness, drowsiness;
  • dry mouth, nose, or throat;
  • upset stomach, loss of appetite, nausea, constipation;
  • blurred vision;
  • sleep problems (insomnia); 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.

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What happens if I miss a dose?

Since NoHist-A is taken as needed, you may not follow a dosing schedule. If you are taking the medication regularly, take the missed dose as soon as you remember. If it is almost time for your next scheduled dose, skip the missed dose. Do not take extra medicine to make up for the missed dose.

This section was rewritten for readability and reviewed for meaning.

What happens if I overdose?

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

Drinking alcohol can increase certain side effects of NoHist-A.

Ask a doctor or pharmacist before using any other cold, cough, allergy, or sleep medicine. Antihistamines and decongestants are in many combination medicines. Taking certain products together can lead to an overdose of a specific drug. Check the label to see if a medicine contains an antihistamine or decongestant.

This medication may cause blurred vision and may affect your thinking or reactions. Be careful if you drive or do anything that requires you to be alert and able to see clearly.

Avoid overheating or dehydration during exercise and in hot weather. Chlorpheniramine and phenyltoloxamine can reduce sweating, which may make you more likely to experience heat stroke.

This section was rewritten for readability and reviewed for meaning.

What other drugs will affect chlorpheniramine, phenylephrine, and phenyltoloxamine?

Tell your doctor about all medicines you take, including prescription and over-the-counter medicines, vitamins, and herbal products. Some medicines can cause unwanted or harmful effects when taken together. Not all possible interactions are listed in this medication guide.

Taking NoHist-A with other drugs that make you sleepy or slow your breathing can make these effects worse. Ask your doctor before taking NoHist-A with a sleeping pill, narcotic pain medicine, muscle relaxer, or medicine for anxiety, depression, or seizures.

This section was rewritten for readability and reviewed for meaning.

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Before you take this medicine: the information on this page is general and may not cover your personal circumstances. Read the label supplied with your medicine and ask a pharmacist or doctor if you are unsure, especially if you are pregnant, breastfeeding, taking other medicines or managing a long-term condition.
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Content is provided for education and is not medical advice. See our medical disclaimer.