Prednisolone for Asthma Flare-Ups: Dose, Course Length and Risks

A short course of prednisolone tablets is the standard treatment for an asthma flare-up that a reliever inhaler cannot settle. The evidence that it works is strong: in randomised trials, a steroid course after emergency treatment cut relapses in the following week by more than half. The evidence that it carries a cost is just as strong. Even a few days of steroid tablets raised the short-term rates of sepsis, blood clots and fractures in a large US study, and every course adds to a lifetime total that tracks with osteoporosis, diabetes, cataracts and pneumonia.

This guide covers when prednisolone is used for asthma, the doses in guidelines, how long a course lasts, whether you need to taper, what the side effects are, and how to keep the number of courses down. It is written for adults and parents who have been given, or may be given, a course. It is not a guide to treating yourself without medical advice.

The short answer

For adults, UK guidance (BTS/SIGN 2014) has recommended prednisolone 40 to 50 mg once a day for at least 5 days, or until recovery, and GINA 2015 1 mg/kg up to 50 mg for 5 to 7 days. For children, doses are set by age or weight, with a maximum of 40 mg a day. Guidelines say a short course can usually be stopped without tapering if you also use a preventer inhaler and do not take steroid tablets long term. Trials found no convincing advantage for higher doses or longer courses. If you need more than the occasional course, the real problem is your day-to-day asthma control, and that is what needs to change.

Question	Answer
What it is	An oral corticosteroid that reduces airway inflammation
When it is used	Moderate or severe asthma flare-ups, usually alongside more reliever and a review of your preventer
Adult dose in guidelines	40 to 50 mg once a day for at least 5 days (BTS/SIGN 2014); GINA 2015: 1 mg/kg, up to 50 mg
Child dose in guidelines	BTS/SIGN 2014: 20 mg (age 2 to 5), 30 to 40 mg (over 5); GINA 2015: 1 to 2 mg/kg up to 40 mg (age 6 to 11)
Taper needed?	Not usually after a short course if you use a preventer inhaler; see below
Main short-term risks	Sleep and mood changes, raised blood sugar, infection, and less often sepsis, blood clots and fractures
Prescription	Prescription only in the UK, US, Canada and Australia

When steroid tablets are used in asthma

Inhaled steroids prevent most asthma symptoms. A flare-up (also called an exacerbation or attack) is a period when symptoms and lung function get worse than usual and stay worse, despite the usual treatment. Mild flare-ups often settle with more reliever and a temporary increase in the preventer. When a flare-up is moderate or severe, or is not settling, guidelines add a short course of steroid tablets.

Steroid tablets do not open the airways quickly. They reduce the swelling and inflammation that drive the flare-up, over hours to days. That is why they come with a reliever, not instead of it, and why a severe attack needs emergency care, not a packet of tablets at home.

Prednisolone, prednisone and how they relate

Prednisolone is the active form. Prednisone is a prodrug that the liver converts into prednisolone. The two are generally treated as interchangeable milligram for milligram in asthma, which is why guidelines often write "prednisolone or prednisone". Prednisolone is the usual choice in the UK, India and Australia. In the US, prednisone tablets are standard and prednisolone is mostly sold as a liquid, often for children.

Dexamethasone as an alternative

Dexamethasone is a longer-acting steroid that is sometimes given as one or two doses instead of a prednisolone course, especially to children, because there are fewer doses to take. A Cochrane review found no convincing difference in outcomes between prednisolone and dexamethasone.

The evidence that it works

Two Cochrane reviews by Rowe and colleagues set out the core evidence. The first looked at people discharged after emergency treatment for asthma. In 6 trials with 374 people (five using oral steroids, one an injection), a steroid course cut relapse in the first week by 62%, cut relapse over 21 days by more than half, and reduced later hospital admissions. As few as ten people needed treatment to prevent one relapse. Side effects in the first 7 to 10 days were rarely reported and did not differ significantly from placebo.

Outcome (steroid vs placebo after an attack)	Relative risk (95% CI)
Relapse needing more care in the first week	0.38 (0.20 to 0.74)
Relapse within 21 days	0.47 (0.25 to 0.89)
Later hospital admission	0.35 (0.13 to 0.95)
Reliever puffs per day	3.3 fewer (1.0 to 5.6 fewer)

The second review looked at steroids given within an hour of arriving at an emergency department. In 12 trials with 863 people, early steroids cut hospital admission (odds ratio 0.40, 95% CI 0.21 to 0.78; about 8 people treated per admission avoided). The effect was largest in people with more severe attacks and in those not already on steroid tablets, and oral steroids worked well in children. No adult trial in that review used the oral route; adults received injections.

Usual doses

Dose recommendations vary between countries and have changed over time, so follow the dose on your prescription. The figures below are those quoted in the 2016 Cochrane review of dosing.

Group	BTS/SIGN 2014 (UK)	GINA 2015 (international)
Adults	40 to 50 mg daily for at least 5 days or until recovery	1 mg/kg daily, up to 50 mg
Children 2 to 5 years	20 mg daily	See local guidance
Children over 5 (GINA: 6 to 11)	30 to 40 mg daily	1 to 2 mg/kg daily, up to 40 mg

Prednisolone is usually taken as a single dose once a day. Many prescribers suggest the morning, because steroids can disturb sleep. Children's doses are rounded to whole tablets or measured liquid doses, so a parent should never work out a child's dose from an adult pack.

Is a bigger or longer course better?

Probably not. The 2016 Cochrane review by Normansell and colleagues included 18 trials with 2,438 adults and children comparing higher with lower prednisolone doses, longer with shorter courses, tapered with non-tapered courses, and prednisolone with dexamethasone. It found no convincing evidence that a higher dose or longer course led to better outcomes, or that prednisolone and dexamethasone differed. The authors rated most evidence low or very low quality, mainly because trials were small, so the honest conclusion is "no proven difference" rather than "proven equal".

In practice, that supports the shortest course that settles the flare-up. GINA 2015 guidance, as quoted in the review, says a 5 to 7 day course in adults and 3 to 5 days in children is usually adequate. Your prescriber may extend it if you are not recovering.

Do you need to taper?

Tapering means stepping the dose down over several days instead of stopping. The idea was to avoid a rebound flare-up and to let the adrenal glands restart their own cortisol production.

The classic trial on this is O'Driscoll 1993. Thirty-five adults admitted with acute asthma took 40 mg of prednisolone a day for 10 days, then either a tapering course or identical placebo tablets over the next week. Morning peak flow was the same in both groups at day 10 (396 vs 391 L/min) and stayed similar through tapering and the following 10 days, as did symptoms and treatment failures. All of them were also using an inhaled steroid. The authors concluded that tapering after a course like this is unnecessary, and the BTS/SIGN and GINA guidance quoted in the Cochrane review says the same for people who use a preventer inhaler, are not on long-term steroid tablets and have had a course of no more than about three weeks.

O'Driscoll 1993 (35 adults)	Active taper	Placebo taper
Morning peak flow at day 10	396 L/min	391 L/min
Difference during or after taper	None significant (p = 0.82)

The US prednisolone label is more cautious than these asthma guidelines: it says the dose should be decreased or stopped gradually when the drug has been given for more than a few days, and that adrenal suppression may last for months after stopping, so extra steroid may be needed during illness, injury or surgery in that period. If you have had repeated courses, tell any doctor treating you for surgery, injury or serious illness. Longer or repeated courses are where this matters most. If you have had several courses close together, take steroid tablets for other conditions, or have been on a course for more than a few weeks, your prescriber will decide whether a taper is needed. Do not stop a long course suddenly on your own.

Side effects of a short course

Some people notice one or more of these during a 5 to 7 day course. They usually settle after the course ends.

• Trouble sleeping, restlessness, mood swings, irritability or, less often, low mood. The label notes that steroids can cause effects ranging from euphoria and insomnia to severe depression and psychosis, and can worsen existing mental health conditions.
• More appetite and some fluid retention.
• Raised blood sugar, which matters if you have diabetes.
• Raised blood pressure, mostly at higher doses.
• Indigestion or stomach discomfort.
• A higher risk of infection, and some infections can be masked. Steroid-related infections are usually mild but can occasionally be severe or fatal.

Serious risks in the month after a course

Short courses are not risk free. Waljee and colleagues studied 1.5 million privately insured US adults aged 18 to 64. Over three years, 21% received at least one prescription for steroid tablets lasting under 30 days. Among people who had one of these events, the rate in the 30 days after starting a course was 5.3 times higher for sepsis, 3.3 times for blood clots and 1.9 times for fractures, compared with those same people's unexposed time. The excess was smaller over the following two months, and it was still present at prednisone-equivalent doses under 20 mg a day.

These are relative risks. Sepsis, clots and fractures are uncommon in this age group, so the absolute increase for any one person is small. But the study covered courses for all reasons, most commonly respiratory infections, back problems and allergies, which is a reminder that steroid tablets should be used when they are needed, not as a routine fix.

Repeated courses add up

The bigger concern in asthma is the total over years. Price and colleagues matched 24,117 adults with asthma who started systemic steroids against 24,117 with asthma who did not, using UK medical records, and followed them for a median of about six to seven years. Those who started steroids had higher rates of osteoporosis or fracture, pneumonia, heart and stroke disease, cataract, sleep apnoea, kidney impairment, depression or anxiety, type 2 diabetes and weight gain.

Outcome (Price 2018)	Adjusted hazard ratio (95% CI)
Osteoporosis or osteoporotic fracture	3.11 (1.87 to 5.19)
Pneumonia	2.68 (2.30 to 3.11)
Cardiovascular or cerebrovascular disease	1.53 (1.36 to 1.72)
Cataract	1.50 (1.31 to 1.73)
Sleep apnoea	1.40 (1.04 to 1.86)
Renal impairment	1.36 (1.26 to 1.47)
Depression or anxiety	1.31 (1.21 to 1.41)
Type 2 diabetes	1.26 (1.15 to 1.37)
Weight gain	1.14 (1.10 to 1.18)

For most harms, risk rose from a lifetime total of about 1.0 to 2.5 g of prednisolone-equivalent steroid, and for some outcomes from only 0.5 to 1 g, which the authors equate to about four lifetime courses. A single 5-day course at 40 mg is 200 mg. This was an observational study of systemic steroids (tablets or injections), so people who needed steroids may have been sicker in other ways, but the dose pattern is consistent with a real effect.

Who needs extra care

The only absolute contraindication on the US prednisolone label is a systemic fungal infection. The label's warnings and precautions add several situations where your prescriber needs to know before you start:

• Active or untreated infections, including tuberculosis or a positive TB test.
• No immunity to chickenpox or measles. Either can be serious or even fatal in people on steroids; seek advice without delay if you are exposed.
• Hepatitis B, past or present, because steroids can reactivate it.
• Threadworm (Strongyloides) infection or travel to areas where it is common, because steroids can trigger a dangerous spread.
• Time in the tropics or unexplained diarrhoea, because the label advises ruling out amoebiasis first. The label also says to avoid steroids in cerebral malaria.
• Children who need repeated or long courses, whose growth should be monitored.
• Diabetes, high blood pressure, osteoporosis, kidney disease, myasthenia gravis, peptic ulcer or bowel conditions such as ulcerative colitis or diverticulitis.
• Glaucoma, cataracts or eye herpes.
• Past depression, psychosis or other mental health conditions, which steroids can make worse.
• Pregnancy or breastfeeding. Uncontrolled asthma is itself a risk in pregnancy, so this is a discussion to have, not a reason to avoid treatment.
• Planned vaccinations. The label advises against vaccination while on steroids, especially at high doses, so ask before any vaccine, particularly a live one.

When a flare-up needs emergency care

Steroid tablets work too slowly for a severe attack. Call emergency services or go to the nearest emergency department if:

• Your reliever is not helping, or you need it again within a few minutes.
• You are too breathless to speak in full sentences, eat or sleep.
• Your lips or fingertips look blue or grey, or you feel drowsy, confused or exhausted.
• Your peak flow is below the danger level in your asthma action plan.

Rescue packs and asthma action plans

Some people with asthma are given a reserve course of prednisolone to keep at home, with written instructions on when to start it. The O'Driscoll authors suggested exactly this: a personal asthma management plan with a reserve course. It works when it is part of a plan agreed with a clinician, with clear thresholds (symptoms or peak flow) for starting the course and for seeking help, and a review after every use. It does not work as a supply to use whenever breathing feels tight.

If you start a reserve course, tell your doctor or asthma nurse within a day or two. Every course is a sign that your preventer plan needs another look.

After the course: fix the cause

The most effective way to avoid the risks above is to need fewer courses. After a flare-up, a review usually looks at:

• Whether you take your preventer every day, and your inhaler technique.
• Triggers: smoking, allergens, infections and work exposures.
• Whether your preventer is strong enough, or a combination inhaler would help. See our budesonide and formoterol guide and the Seroflo and generic Advair strengths guide.
• Whether a triple inhaler is worth considering. The trials found better lung function but no significant drop in attacks; see Breztri vs Trelegy.
• Whether add-on tablets such as montelukast fit (read our montelukast side effects guide first), or a referral for severe asthma and biologics.

US cost: prednisolone tablets are the expensive option

For readers in the US there is a quirk worth knowing. Prednisone tablets are among the cheapest drugs a US pharmacy buys. Generic prednisolone 5 mg tablets are not.

5-day course at 40 mg a day (US)	NADAC per unit (week of 7 Oct 2026)	Units	Course cost
Prednisolone 5 mg tablets	$8.48 per tablet	40 tablets	$339.36
Prednisolone 15 mg/5 mL solution	$0.568 per mL	66.7 mL	$37.84
Prednisone 20 mg tablets	$0.064 per tablet	10 tablets	$0.64

NADAC is the federal survey of what pharmacies pay, not the counter price. Even so, a US adult prescribed a steroid burst for asthma will normally get prednisone, and there is no reason to import prednisolone tablets to replace it.

Prednisolone brands and strengths

Outside the US, prednisolone is sold as plain tablets and as brands. In India, common brands include Omnacortil 5 mg, 10 mg, 20 mg and 40 mg, Wysolone 5 mg and Predniheal 5 mg. A 40 mg dose can be one 40 mg tablet, two 20 mg or eight 5 mg tablets, and mixing strengths is a common source of dosing errors. Check the strength on every strip, and keep to the dose and number of days on your prescription. SafeRxPills supplies prednisolone as a prescription medicine; it should be part of a plan agreed with your doctor, not a substitute for one.

For the full range of asthma guides and treatments, see the asthma hub.

Sources

• Rowe BH et al. Corticosteroids for preventing relapse following acute exacerbations of asthma. Cochrane Database Syst Rev 2007. PMID 17636617. PubMed
• Rowe BH et al. Early emergency department treatment of acute asthma with systemic corticosteroids. Cochrane Database Syst Rev 2001. PMID 11279756. PubMed
• Normansell R et al. Different oral corticosteroid regimens for acute asthma. Cochrane Database Syst Rev 2016. PMID 27176676. Cochrane Library
• O'Driscoll BR et al. Double-blind trial of steroid tapering in acute asthma. Lancet 1993. PMID 8094111. PubMed
• Waljee AK et al. Short term use of oral corticosteroids and related harms among adults in the United States: population based cohort study. BMJ 2017. PMID 28404617. PubMed
• Price DB et al. Adverse outcomes from initiation of systemic corticosteroids for asthma: long-term observational study. J Asthma Allergy 2018. PMID 30214247. PubMed
• Prednisolone oral solution US prescribing information (TruPharma), revised September 2026: Contraindications, Warnings and Precautions. DailyMed
• Centers for Medicare and Medicaid Services. National Average Drug Acquisition Cost (NADAC), 2026 file, week of 7 October 2026. data.medicaid.gov

This guide is for information only and is not medical advice. Prednisolone is a prescription medicine. Take it only as prescribed, and seek emergency care for a severe asthma attack.