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Generic name: guaifenesingwye-FEN-e-sin ]
Brand names: Allfen, Bidex-400, Diabetic Tussin Chest Congestion, Fenesin IR, Geri-Tussin Expectorant, ... show all 23 brands
Drug class: Expectorants

Medically reviewed by on Dec 21, 2023. Written by Cerner Multum.

What is Bidex-400?

Bidex-400 is used to reduce chest congestion caused by the common cold, flu, or chronic bronchitis.

Bidex-400 helps loosen congestion in your chest and throat, making it easier to cough out through your mouth.

There are many brands and forms of guaifenesin available. Not all brands are listed on this leaflet.

Bidex-400 may also be used for purposes not listed in this medication guide.

Bidex-400 side effects

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

Common side effects of Bidex-400 may include:

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 Bidex-400 if you have health problems or use other medications, or if you are pregnant or breast-feeding.

Before taking this medicine

You should not use Bidex-400 if you are allergic to it.

Ask a doctor or pharmacist if it is safe for you to use this medicine if you have other medical conditions.

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

You should not breast-feed while using Bidex-400.

How should I take Bidex-400?

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).

To use Bidex-400 granules, pour out the entire packet onto your tongue and swallow without chewing.

Call your doctor if your symptoms do not improve after 7 days, or if you have a fever, rash, or headaches.

Bidex-400 can affect the results of certain medical tests. Tell any doctor who treats you that you are using Bidex-400.

Store at room temperature away from moisture and heat. Do not freeze.

What happens if I miss a dose?

Since cough or cold medicine 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.

What happens if I overdose?

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

What should I avoid while taking Bidex-400?

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

Avoid driving or hazardous activity until you know how Bidex-400 will affect you. Your reactions could be impaired.

What other drugs will affect Bidex-400 ?

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.

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Further information

Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use this medication only for the indication prescribed.

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.