Prednisolone and prednisone are not the same drug, but they’re closely related. Prednisone is inactive on its own. Your liver converts it into prednisolone, which is the form that actually reduces inflammation and suppresses the immune system. At equal doses, they produce the same effects in most people, which is why they’re often treated as interchangeable. But the distinction matters in specific situations, particularly for people with liver problems, for children, and for cats.
How Your Body Converts One Into the Other
When you swallow a prednisone tablet, it travels to your liver, where an enzyme called CYP3A4 converts it into prednisolone. Prednisolone is the biologically active compound that enters your bloodstream and does the work of calming inflammation, dialing down immune responses, and managing conditions like asthma, arthritis, and autoimmune disorders. Prednisone is essentially a “prodrug,” a pill designed to become the real medication once your body processes it.
Prednisolone, on the other hand, is already in its active form. It doesn’t need your liver to do anything to it before it starts working. This is the key chemical difference between the two, and it’s the reason doctors sometimes choose one over the other.
Dosing Is Milligram for Milligram
For most adults with normal liver function, the two drugs are functionally equivalent. According to corticosteroid equivalency tables used in clinical practice, 1 mg of prednisone equals 1 mg of prednisolone. Both have the same duration of action (12 to 36 hours) and the same anti-inflammatory potency. If your doctor switches you from one to the other at the same dose, you should not notice a difference in how well the medication works or how you feel on it.
Side Effects Are the Same
Because prednisolone is what your body ends up with either way, both drugs carry identical side effects. Short-term use can cause stomach irritation, trouble sleeping, fluid retention, mood changes, increased appetite, and weight gain. Long-term use raises the risk of bone loss, thinning skin, high blood pressure, and elevated blood sugar. Both also require a gradual taper if you’ve been taking them for more than a week or two, because stopping abruptly can trigger withdrawal symptoms as your adrenal glands readjust.
When Liver Function Changes the Equation
The one-to-one equivalence between prednisone and prednisolone breaks down when the liver isn’t working well. A study published in the journal Gut measured blood levels in patients with cirrhosis and found that people with severely impaired liver function converted prednisone into prednisolone at roughly half the rate of those with mild impairment. Their prednisolone blood levels after taking prednisone were only 53% of what they should have been, while unconverted prednisone levels were 74% higher than expected.
In contrast, when these same patients took prednisolone directly, their blood levels were normal regardless of how damaged their liver was. This is why prednisolone is the preferred choice for anyone with significant liver disease, including people with cirrhosis, severe hepatitis, or other conditions that compromise liver enzyme activity. If you take prednisone and have liver problems, you may simply not be getting the full benefit of the medication.
Why Children Usually Get Prednisolone
Young children who need a corticosteroid for croup, asthma flares, or allergic reactions are typically prescribed prednisolone in liquid form rather than prednisone tablets. The practical reason is straightforward: small children can’t reliably swallow pills, and prednisolone is widely available as a liquid.
Not all liquid prednisolone is created equal, though. The base form of prednisolone tastes intensely bitter, and children are more sensitive to bitter flavors than adults. A different formulation, prednisolone sodium phosphate, tastes significantly better and leads to better adherence. If your child spits out their steroid liquid or refuses to take it, asking the pharmacist to dispense the sodium phosphate version can make a real difference.
Cats Need Prednisolone, Not Prednisone
If you’ve landed on this article because your vet prescribed one of these for your cat, this distinction matters. Cats have a less efficient liver conversion pathway than dogs or humans, which means they don’t reliably turn prednisone into its active form. Dogs can take either drug interchangeably, similar to humans. But cats should receive prednisolone directly to ensure they actually absorb the active medication. If your cat has been prescribed prednisone rather than prednisolone, it’s worth confirming with your vet that the correct drug was intended.
Which One You’ll Likely Be Prescribed
In the United States, prednisone is prescribed far more commonly than prednisolone for adults. It’s widely available, inexpensive, and works identically for anyone with a healthy liver. Prednisolone is more common in the UK, Australia, and several other countries as the default corticosteroid. Neither is inherently better. Your doctor’s choice usually comes down to local prescribing habits, the available formulations (tablet vs. liquid), and whether you have any liver concerns that would make prednisolone the safer bet.
If you’re switching between the two for any reason, the transition is simple: same dose, same schedule, same expected results. The only people who need to pay close attention to which one they’re taking are those with liver disease, parents giving liquid steroids to young children, and cat owners.