Inhalers and Steroids

TL;DR. Inhalers put a small dose exactly where it is needed, so a microgram-level inhaled steroid does what would take milligrams orally. The persistent problem is that most people use them wrongly: studies repeatedly find the majority of patients make at least one critical error, and a spacer plus good technique often achieves more than a stronger drug. Asthma treatment changed fundamentally in recent years: relying on a blue reliever alone is now recognised as dangerous, and every asthma patient should be on an inhaled steroid. Oral steroids are transformative and expensive in side effects, and must never be stopped abruptly after prolonged use.

1. Why inhalation works

Delivering a drug directly to the airway means a tiny dose achieves a high local concentration with minimal systemic exposure. A typical inhaled steroid dose is measured in micrograms; the oral equivalent would be milligrams, a thousandfold difference, with all the side effects that brings.

Particle size decides where it lands. Particles above about 5 micrometres deposit in the mouth and throat; 1 to 5 micrometres reach the lower airways; below 1 micrometre are largely exhaled. This is the entire engineering problem of inhaler design.

Even with good technique, only 10 to 40 percent of the dose reaches the lungs. Most of the rest is swallowed, which is why rinsing your mouth matters.

2. The devices

The two techniques are opposites, and mixing them up is the commonest error in people who use both types. A pMDI needs a slow and steady breath in over 4 to 5 seconds. A dry powder inhaler needs a quick and deep breath. Using a slow breath on a DPI fails to disaggregate the powder; using a fast breath on a pMDI deposits the drug in your throat.

The correct pMDI technique:

1. Remove cap, shake well.
2. Breathe out fully, away from the inhaler.
3. Seal lips around the mouthpiece.
4. Start breathing in slowly, then press the canister once while continuing to breathe in slowly and deeply over 4 to 5 seconds.
5. Hold your breath for up to 10 seconds.
6. Wait 30 seconds before a second puff.
7. Rinse your mouth and spit if it contains a steroid.

Use a spacer. For pMDIs, a spacer improves lung deposition substantially, removes the coordination requirement, and reduces oropharyngeal deposition and therefore thrush and hoarseness. Spacers are as effective as nebulisers for most acute asthma in children and adults, and are used in emergency departments for that reason. Wash a spacer monthly in warm soapy water and let it air dry without rinsing or wiping: the residual detergent film reduces static, which otherwise attracts a substantial fraction of the drug to the walls.

Studies consistently find that 50 to 90 percent of patients make at least one critical inhaler error. Technique is worth checking at every review, and this is often more valuable than escalating treatment.

3. The drugs in inhalers

Relievers (bronchodilators)

Short-acting beta-2 agonists (SABA): salbutamol (albuterol), terbutaline. Relax airway smooth muscle within minutes, lasting 4 to 6 hours. Blue inhalers.

Side effects: tremor, palpitations, headache, and, at high doses, low potassium.

Short-acting muscarinic antagonist: ipratropium, used more in COPD.

Preventers (controllers)

Inhaled corticosteroids (ICS): beclometasone, budesonide, fluticasone, ciclesonide. Brown, orange, or red inhalers, though colour conventions are unreliable across countries.

They reduce airway inflammation over days to weeks. They do nothing for an acute attack, which is exactly why people under-use them: the benefit is invisible.

Side effects at inhaled doses are mostly local: oral thrush, hoarseness (dysphonia), and cough. Both are largely prevented by a spacer and by rinsing and spitting. Systemic effects (adrenal suppression, reduced bone density, cataracts, small growth effects in children) occur mainly at high doses.

Long-acting beta-2 agonists (LABA): salmeterol, formoterol. Must never be used alone in asthma: trials found increased asthma deaths with LABA monotherapy, and they are only used in combination with an inhaled steroid. Formoterol is unusual in having a rapid onset as well as long duration, which underpins the MART regimen below.

Long-acting muscarinic antagonists (LAMA): tiotropium, glycopyrronium. Mainstay in COPD, add-on in asthma.

Combination inhalers (ICS+LABA, or triple ICS+LABA+LAMA) improve adherence and guarantee the steroid is taken.

4. The change in asthma treatment

This is the most important practical update in this chapter.

For decades, mild asthma was treated with a blue reliever "as needed" and a preventer added later. That approach is now considered unsafe.

Why it changed:

• Over-reliance on SABA is associated with increased asthma deaths. The UK's National Review of Asthma Deaths found that a substantial proportion of people who died had been prescribed excessive reliever inhalers and inadequate preventers.
• Even mild asthma involves airway inflammation, and relievers do nothing about it. They mask worsening control.
• The SYGMA and Novel START trials showed that as-needed combination budesonide-formoterol reduced severe exacerbations compared with as-needed SABA, and compared favourably with daily steroid plus as-needed SABA in real-world adherence.

Current guidance (GINA and others):

• Every person with asthma should receive an inhaled corticosteroid, either regularly or in a combination reliever.
• SABA-only treatment is no longer recommended for anyone.
• MART (maintenance and reliever therapy) uses a single budesonide-formoterol inhaler for both daily control and symptom relief, so every reliever dose also delivers a steroid.

A practical warning sign: needing your reliever three or more times a week, or getting through more than about three reliever inhalers a year, means your asthma is not controlled and you need a review. Using a reliever daily is not "managing well."

Asthma action plans (written plans setting out daily treatment, what to do when symptoms worsen, and when to seek emergency help) reduce hospital admissions and deaths and are still not given to most patients. Ask for one.

5. Oral and systemic steroids

Prednisolone, dexamethasone, hydrocortisone

Corticosteroids are synthetic analogues of cortisol. They suppress inflammation and immune activity broadly, by altering gene transcription. They are among the most useful drugs in medicine and among the most costly in side effects.

Uses: asthma and COPD exacerbations, autoimmune and inflammatory disease, allergic reactions, some cancers, transplant immunosuppression, adrenal insufficiency replacement, and, since the RECOVERY trial, severe COVID-19, where dexamethasone reduced mortality in ventilated patients and became standard care worldwide within days of publication.

Side effects, by duration:

Even short courses are not free. Studies of short-course oral steroids in outpatients have found increased rates of sepsis, venous thromboembolism, and fracture in the following 30 days. They remain worth it when indicated.

Adrenal suppression is the crucial safety issue. Exogenous steroid suppresses the hypothalamic-pituitary-adrenal axis, and the adrenal glands stop producing cortisol. After roughly three weeks of treatment (sooner at high doses), they cannot restart immediately.

Stopping steroids abruptly after prolonged use can cause an adrenal crisis: collapse, vomiting, low blood pressure, low sodium, and death. Courses beyond about three weeks must be tapered. Anyone on long-term steroids should carry a steroid emergency card, and needs increased doses during illness, injury, or surgery, because the body's normal cortisol surge in stress cannot happen. Sick day rules for steroids are the mirror image of those for metformin: more, not less.

Bone protection: anyone expected to take steroids for over three months is usually assessed for bone protection with calcium, vitamin D, and often a bisphosphonate.

Other systemic steroid routes: joint injections (helpful, limited in number because of cartilage effects), and topical steroids for skin.

6. Topical steroids

Graded by potency, and the potency-plus-site combination is what matters:

Steroid phobia is a real and documented problem that causes undertreatment of eczema, worse disease, and more infections. Topical steroids used correctly, at appropriate potency, for appropriate durations are safe and effective. The harms come from prolonged use of potent steroids on thin skin (face, genitals, flexures): skin thinning, striae, telangiectasia, and, on the face, perioral dermatitis.

The fingertip unit is the practical dosing measure: the amount squeezed from the fingertip to the first crease, roughly 0.5 g, which treats an area of about two adult palms.

Topical steroid withdrawal ("red skin syndrome") is a recognised phenomenon after prolonged potent steroid use, particularly on the face, and it is also invoked far beyond the evidence in online communities in ways that lead people to abandon effective treatment. If you are worried, ask a dermatologist rather than the internet.

Emollients are the foundation of eczema treatment, used generously and frequently regardless of whether steroids are needed. Apply emollient and steroid at different times, with roughly 30 minutes between them.

7. COPD, briefly

Different from asthma in an important respect: airflow obstruction is largely fixed rather than reversible, and inflammation responds less to steroids.

Treatment is built on LAMA and LABA bronchodilators, with inhaled steroids added mainly for people with frequent exacerbations or eosinophilic inflammation, because in COPD they increase pneumonia risk.

The interventions that actually change the course of COPD: stopping smoking (the only one that alters decline in lung function), pulmonary rehabilitation (as effective as most drugs for symptoms and quality of life, and consistently under-provided), vaccination, and, in selected patients, long-term oxygen.

8. Practical guidance

• Have your inhaler technique checked, ideally at every review. Most people are doing something wrong.
• Use a spacer with a pMDI. Wash it monthly, air dry, do not rinse or wipe.
• Rinse and spit after steroid inhalers.
• Remember: pMDI slow and steady, DPI quick and deep.
• If you use a blue reliever three or more times a week, get reviewed.
• Get a written asthma action plan.
• Never stop long-term steroids abruptly, and carry a steroid card.
• Increase steroid dose during illness if you are on long-term treatment, and know when to seek help.
• Do not undertreat eczema out of steroid fear. Use enough, at the right potency, for long enough, on top of generous emollients.

9. The bottom line

• Inhalation delivers micrograms where oral treatment would need milligrams, and most people use their inhalers wrongly, which is often the real problem rather than the drug.
• pMDI: slow and steady. DPI: quick and deep. Use a spacer with a pMDI; it is as good as a nebuliser for most acute asthma.
• Asthma treatment changed: nobody should be on a reliever alone. Every asthma patient needs an inhaled steroid, and heavy reliever use is a marker for risk of death.
• Oral steroids are transformative and expensive: even short courses carry measurable risks, and long courses cause adrenal suppression that makes abrupt stopping dangerous.
• Topical steroids are widely underused because of unfounded fear. Match potency to site, use the fingertip unit, and build on emollients.
• In COPD, stopping smoking and pulmonary rehabilitation do more than any inhaler.

Sources and notes

Doses, cautions, and interactions follow the British National Formulary and the electronic Medicines Compendium; US figures follow FDA labelling. Inhaler device technique, particle size and lung deposition, and spacer benefit follow the Asthma + Lung UK and NICE guidance and Cochrane reviews comparing spacers with nebulisers. Critical error rates follow Sanchis et al., Chest, 2016, which found little improvement over 40 years. The SABA-only reversal follows GINA strategy reports from 2019 onward, the UK National Review of Asthma Deaths (Royal College of Physicians, 2014), and the SYGMA 1 and 2 trials (O'Byrne et al. and Bateman et al., NEJM, 2018) plus Novel START (Beasley et al., NEJM, 2019). LABA monotherapy mortality follows SMART and the FDA analyses. Asthma action plans reducing admissions follow Gibson et al.'s Cochrane review. Corticosteroid mechanisms and adverse effects follow standard endocrinology; short-course steroid harms follow Waljee et al., BMJ, 2017. Dexamethasone in COVID-19 is the RECOVERY trial, NEJM, 2021. Adrenal suppression and steroid emergency cards follow the Society for Endocrinology and NHS England guidance. Topical steroid potency, fingertip units, and steroid phobia follow NICE eczema guidance and Charman and Williams' work; topical steroid withdrawal follows the 2021 MHRA review. COPD management follows GOLD reports, with pulmonary rehabilitation evidence from Cochrane.

Open questions. How much of asthma outcome improvement is attributable to the drug change versus better adherence and review is hard to separate. Topical steroid withdrawal is recognised by regulators and its frequency and definition remain poorly characterised.

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