What Is Mannitol?

Mannitol is an osmotic diuretic — a medication that works by drawing water out of swollen tissues and into the bloodstream, where the kidneys can then flush it out as urine.

It is one of the most important emergency medications used in hospitals to treat dangerous swelling in the brain (cerebral edema) and elevated pressure in the eyes (intraocular pressure). An inhaled form called Bronchitol is also available for cystic fibrosis patients.

Key Facts at a Glance

• Generic name: Mannitol
• Brand names: Osmitrol (IV), Bronchitol (inhalation for CF), Aridol (bronchial challenge testing)
• Drug class: Osmotic diuretic
• Manufacturers: Baxter Healthcare (Osmitrol IV), ICU Medical (IV solutions), Chiesi/Pharmaxis (Bronchitol)
• Controlled substance: No — Mannitol is not a controlled substance
• Generic available: Yes, for IV formulations

What Is Mannitol Used For?

Mannitol has several FDA-approved uses and some common off-label uses:

FDA-Approved Uses

• Reducing intracranial pressure (ICP) — Used in head trauma, brain tumors, stroke, and neurosurgery to reduce dangerous brain swelling
• Reducing intraocular pressure (IOP) — Used when eye pressure is dangerously high and other treatments have not worked
• Cystic fibrosis maintenance therapy — Bronchitol (inhaled Mannitol) helps improve lung function by hydrating airway secretions
• Bronchial hyperresponsiveness testing — Aridol is used to test for asthma-like airway reactivity

Common Off-Label Uses

• Promoting diuresis in acute kidney injury
• Helping the body excrete toxic substances
• Priming heart-lung bypass machines during surgery
• Preventing low blood pressure during dialysis
• Urological irrigation during surgical procedures

For more about how Mannitol works at the molecular level, see our guide on Mannitol's mechanism of action.

How Is Mannitol Taken?

Mannitol is not taken as a pill you pick up at the pharmacy. Here is how each form is administered:

IV Mannitol (Osmitrol and Generics)

This is given by intravenous infusion in a hospital or clinical setting by trained healthcare professionals. Key details:

• Available in concentrations of 5%, 10%, 15%, 20%, and 25%
• The 20% solution is the most commonly used
• Must be filtered through an inline filter to catch any crystals that may have formed
• Typical dose for intracranial pressure: 0.25 to 2 g/kg infused over 30 to 60 minutes
• Typical dose for intraocular pressure: 1.5 to 2 g/kg as a 15-25% solution

Inhaled Mannitol (Bronchitol)

Used for cystic fibrosis, Bronchitol comes as 40 mg dry powder capsules inhaled via a special device:

• Standard dose: 400 mg twice daily (ten 40 mg capsules per dose)
• An initiation dose assessment is required before starting treatment
• Used as add-on maintenance therapy alongside other CF treatments

Who Should Not Take Mannitol?

Mannitol is contraindicated (should not be used) in patients with:

• Established anuria from severe kidney disease
• Severe pulmonary congestion or active pulmonary edema
• Active intracranial bleeding (except during craniotomy)
• Severe dehydration
• Severe heart failure
• Known allergy to Mannitol

It should be used with extra caution in elderly patients, pregnant women (Category C), and anyone with compromised kidney function. For a complete look at potential risks, see our guide to Mannitol side effects.

How Much Does Mannitol Cost?

The cost of Mannitol varies significantly depending on the formulation:

IV Mannitol

• Generic 20% 250 mL bag: approximately $12 to $30
• Generic 20% 500 mL bag: approximately $25 to $60
• Generic 25% 1250 mL: approximately $135

In most cases, IV Mannitol costs are included in your hospital bill and are not billed to you separately at a pharmacy. Insurance covers it as part of inpatient or outpatient facility charges.

Bronchitol (Inhaled Mannitol)

• Without insurance: approximately $3,826 for a 28-day supply (560 capsules)
• Most insurance plans cover it with prior authorization
• Chiesi CareConnect offers patient support for eligible patients

For ways to lower your costs, check out our guide to saving money on Mannitol.

Current Availability

As of 2026, IV Mannitol continues to face supply challenges. ICU Medical's premixed 20% bags (250 mL and 500 mL) have been on allocation since 2023. This is part of a broader pattern of IV fluid shortages that has affected hospitals nationwide.

If you are having trouble finding Mannitol, Medfinder can help you check pharmacy availability in your area. For more on the shortage, read our Mannitol shortage update for 2026.

Final Thoughts

Mannitol is a critical hospital medication that saves lives by reducing dangerous swelling in the brain and eyes. While most patients will receive it in a hospital setting without needing to think about pharmacy logistics, understanding what it is, how it works, and what it costs puts you in a better position to advocate for your care.

If you are looking for a specialist who prescribes Mannitol, our guide to finding a prescribing doctor can help.