When Mannitol Isn't Available, There Are Other Options

Mannitol has been a go-to medication in emergency rooms and intensive care units for decades. But with the ongoing Mannitol shortage, many patients and healthcare teams are looking for alternatives that can get the job done.

The good news? There are several well-studied medications that can serve as substitutes for Mannitol, depending on why it was prescribed. In this guide, we'll walk you through what Mannitol does, how it works, and the best alternatives available in 2026.

What Is Mannitol?

Mannitol is an osmotic diuretic — a medication that pulls excess water out of swollen tissues and into the bloodstream, where your kidneys can remove it through urine. It's been FDA-approved since 1964 and is one of the most commonly used drugs in critical care.

Doctors primarily use Mannitol to:

• Reduce intracranial pressure (brain swelling) after head injuries, strokes, or brain surgery
• Lower intraocular pressure (eye pressure) in acute glaucoma or before eye surgery
• Promote diuresis (urine output) in acute kidney injury
• Help the body eliminate toxins more quickly

Mannitol is given by IV infusion in a hospital setting. It's not a pill you take at home, which is why the shortage mainly affects hospitals and clinical facilities.

How Does Mannitol Work?

When Mannitol is infused into your bloodstream, it increases the concentration of your blood plasma (makes it more "thick" with dissolved particles). This creates an osmotic gradient — essentially, water naturally flows from areas of low concentration to high concentration.

So water gets pulled out of swollen brain tissue, out of the fluid inside your eyes, and into your blood vessels. From there, Mannitol travels to your kidneys, where it's filtered out along with all that extra water. The result is reduced swelling and increased urine output.

For the inhaled form (Bronchitol), the mechanism is different — it hydrates airway mucus in cystic fibrosis patients, making it easier to cough up and clear from the lungs.

Alternatives to Mannitol

If your healthcare team can't get Mannitol, here are the most commonly used alternatives. Important: Only your doctor can decide which alternative is right for your situation. These are not interchangeable without medical guidance.

1. Hypertonic Saline (3%, 7.5%, or 23.4%)

Hypertonic Saline is the most widely used alternative to Mannitol for reducing intracranial pressure. It's essentially a highly concentrated salt solution given by IV.

How it works: Like Mannitol, Hypertonic Saline draws water out of swollen brain tissue by creating an osmotic gradient. However, it does this without causing the same degree of diuresis (water loss through urine), which can be an advantage in patients who are already dehydrated or have low blood pressure.

Key facts:

• Multiple studies show Hypertonic Saline is at least as effective as Mannitol for reducing intracranial pressure, and some research suggests it may be superior
• Available in several concentrations — 3% is most common, while 23.4% is used for severe, acute brain swelling
• Generally more available than Mannitol during the current shortage
• May be safer in patients with kidney problems, since it doesn't rely on kidney filtration the same way Mannitol does

2. Furosemide (Lasix)

Furosemide is a loop diuretic — a powerful medication that makes the kidneys produce more urine by blocking sodium reabsorption. It's one of the most commonly used drugs in medicine.

How it's used as a Mannitol alternative: Furosemide is sometimes used alongside or instead of Mannitol to reduce fluid overload and, in some cases, to help lower intracranial pressure. It's not a direct replacement for Mannitol's osmotic mechanism, but it can help manage the same underlying problems.

Key facts:

• Very widely available and inexpensive (generic Furosemide costs just a few dollars)
• Can be given IV or by mouth
• Often used in combination with Mannitol or Hypertonic Saline rather than as a sole replacement
• Does not cross the blood-brain barrier, so its effect on brain swelling is indirect

3. Glycerol (Glycerin)

Glycerol is another osmotic agent that has been used for decades to reduce intracranial and intraocular pressure. It can be given orally or intravenously.

Key facts:

• Works similarly to Mannitol by creating an osmotic gradient
• Can be taken by mouth, which is an advantage when IV access isn't available
• Less commonly used than Mannitol or Hypertonic Saline in modern practice
• May cause nausea and elevated blood sugar
• Can be an option when both Mannitol and Hypertonic Saline are unavailable

4. Acetazolamide (Diamox)

Acetazolamide is a carbonic anhydrase inhibitor that reduces the production of cerebrospinal fluid (the fluid that surrounds the brain and spinal cord) and aqueous humor (the fluid inside the eye).

Key facts:

• Commonly used to reduce intraocular pressure in glaucoma — this is where it most directly substitutes for Mannitol
• Also used to treat idiopathic intracranial hypertension (pseudotumor cerebri)
• Available as oral tablets and IV injection
• Works by a completely different mechanism than Mannitol
• Not as effective for acute, severe brain swelling from trauma — better suited for chronic or subacute conditions

What About Bronchitol Alternatives?

If you use Bronchitol (inhaled Mannitol) for cystic fibrosis and can't find it, talk to your pulmonologist about alternatives such as:

• Hypertonic Saline (7%) nebulized — widely used for airway clearance in CF
• Dornase Alfa (Pulmozyme) — an inhaled enzyme that thins mucus

Both of these are established CF treatments and may be suitable substitutes depending on your specific situation.

How to Find Mannitol in Stock

Before switching to an alternative, it's worth checking whether Mannitol might be available from another source. Medfinder can help you track real-time Mannitol availability and may help your healthcare facility locate supply.

Final Thoughts

Mannitol is a proven, effective medication — but when it's not available, there are real alternatives that your healthcare team can turn to. Hypertonic Saline is the closest direct substitute for most of Mannitol's uses, while Furosemide, Glycerol, and Acetazolamide each play a role depending on the specific condition being treated.

The most important step is to have an open conversation with your doctor about what options are available and what makes the most sense for your care. And don't forget to check Medfinder for the latest availability updates.

Learn more:

• Mannitol Shortage Update: What Patients Need to Know in 2026
• How Does Mannitol Work? Mechanism of Action Explained
• Mannitol Side Effects: What to Expect