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Aztreonam (inhalation)

Generic name: aztreonam (inhalation) [ az-TREE-oh-nam ]
Brand name: Cayston
Dosage form: inhalation powder for reconstitution (75 mg)
Drug class: Miscellaneous antibiotics

Medically reviewed by on Sep 18, 2023. Written by Cerner Multum.

What is aztreonam?

Aztreonam is an antibiotic that fights bacteria.

Aztreonam inhalation is used to improve breathing symptoms in people with cystic fibrosis and a lung infection caused by bacteria called Pseudomonas aeruginosa.

aztreonam is for use in adults and children at least 7 years old with a 1-second forced expiratory volume (FEV1) between 25% and 75%.

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

Aztreonam 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.

Aztreonam may cause serious side effects. Call your doctor at once if you have:

  • bronchospasm (wheezing, cough, chest tightness, trouble breathing); or

  • any new or worsening breathing problems.

Common side effects of aztreonam may include:

  • wheezing, chest discomfort;

  • stomach pain, vomiting;

  • fever (more common in children); or

  • cough, sore throat, stuffy nose.

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.


Use only as directed. Tell your doctor if you use other medicines or have other medical conditions or allergies.

Before taking this medicine

You should not use aztreonam if you are allergic to it.

Tell your doctor if you are allergic to any type of antibiotic.

Tell your doctor if you are pregnant or breastfeeding.

Aztreonam should not be given to a child younger than 7 years old.

How should I use aztreonam?

Follow all directions on your prescription label and read all medication guides or instruction sheets. Use the medicine exactly as directed.

Use aztreonam only with an Altera brand nebulizer. Do not mix other medicines with aztreonam in the nebulizer.

Be sure you understand how to properly mix this medicine with the liquid (diluent) before pouring it into the nebulizer. Prepare your dose only when you are ready to use the nebulizer. Call your pharmacist if the medicine looks cloudy or has particles in it.

Throw away the medicine ampule (bottle) after one use, even if there is still medicine left inside.

Aztreonam inhalation is usually given 3 times daily at 4-hour intervals for 28 days. Follow your doctor's dosing instructions very carefully.

You may need to use a bronchodilator medicine before each dose of aztreonam. Use only the bronchodilator your doctor has prescribed and carefully follow all instructions about timing the doses in relation to your aztreonam dose.

If you use a short-acting bronchodilator such as albuterol or levalbuterol (Combivent, DuoNeb, ProAir, Proventil, Respimat, Ventolin, Xoponex): Use the bronchodilator between 15 minutes and 4 hours before using aztreonam.

If you use a long-acting bronchodilator such as salmeterol or formoterol (Advair, Breo, Dulera, Foradil, Serevent, Symbicort): Use the bronchodilator between 30 minutes and 12 hours before using aztreonam.

If you use a medicine to clear mucus from your lungs, use it after using a bronchodilator and before using aztreonam.

Keep using aztreonam for the entire 28 days, even if your symptoms quickly improve. Skipping doses could make your infection resistant to medication. Aztreonam will not treat a viral infection (flu or a common cold).

Store the medicine and diluent in the refrigerator. Do not freeze. Do not use past the expiration date on the label.

You may store the medicine and diluent at room temperature for up to 28 days, protected from heat and light. Do not use the medicine if it has been at room temperature for longer than 28 days.

What happens if I miss a dose?

Use the medicine as soon as you can, then wait 4 hours before using your next dose. Do not use two doses at one time.

Even if you miss a dose, try and use all of your doses for the day as long as they are spaced at least 4 hours apart.

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 using aztreonam?

Follow your doctor's instructions about any restrictions on food, beverages, or activity.

What other drugs will affect aztreonam?

If you use other inhaled medications, you may need to use them in a certain order while using aztreonam inhalation. Ask your doctor for specific instructions about when to use your other medications in relation to your aztreonam inhalation doses.

There may be other drugs that can interact with aztreonam. Tell your doctor about all medications you use. This includes prescription, over-the-counter, vitamin, and herbal products. Do not start a new medication without telling your doctor.

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.