Lyng Pharmacy
Medicines A–Z · Combination inhaler

Combination Inhalers (Fostair, Symbicort, Seretide, Trelegy)

Preventer plus long-acting reliever in one device · Written by the Lyng Pharmacy team, based on NHS and BNF guidance · Updated August 2026
Also sold asFostair, Symbicort, Seretide, Relvar, Trelegy, Trimbow
Type of medicineCombination inhaler
Available asMetered dose inhalers and dry powder devices
How you get itPrescription only

A combination inhaler contains an inhaled steroid plus a long-acting bronchodilator, and sometimes a third medicine. They simplify treatment into one device — but the instructions differ substantially between brands, and using one the way you used the last is a common source of poor control.

What is in them

They are preventers. Most are taken every day whether or not you have symptoms.

MART — when the preventer is also the reliever

Some regimens using Fostair or Symbicort are prescribed as MART: maintenance and reliever therapy. You take a regular daily dose and use the same inhaler for symptom relief instead of a separate blue inhaler.

MART only works with specific inhalers. Never use a Seretide, Relvar, Trelegy or Trimbow inhaler as a reliever. If you have been put on MART you should have a written plan stating the maximum puffs in 24 hours — if you do not have one, ask for it.

Technique and mouth care

Rinse your mouth with water and spit it out after every dose. This prevents oral thrush and hoarseness, the commonest side effects.

Metered dose inhalers work far better with a spacer. Dry powder devices need a fast, deep breath in — the opposite of the slow steady breath a metered dose inhaler needs, which is why swapping device types without being shown the technique often goes wrong.

Ask us to check your technique. It takes two minutes and is one of the highest-value things we do.

Side effects and warnings

Oral thrush, hoarseness, sore throat, headache, tremor and palpitations are the common ones.

Report worsening breathlessness, needing your reliever more often, or breathing that gets worse immediately after using the inhaler.

Needing a reliever three or more times a week means control is not good enough — book an asthma review rather than accepting it. Have a written asthma or COPD action plan, and an annual review.

Call 999 if you cannot speak in full sentences, your reliever is not helping, your lips look blue, or breathing is exhausting you.

Always read the label. This page is general information, not advice for your situation. Doses, warnings and interactions differ between products and between people. Check the leaflet inside your medicine, and ask our pharmacist if anything is unclear — that conversation is free and takes two minutes.

Questions about Combination inhalers?

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Frequently asked questions

Can I use my combination inhaler as a reliever?
Only if you are on a MART regimen using a specific inhaler such as Fostair or Symbicort, with a written plan. Never use Seretide, Relvar, Trelegy or Trimbow as a reliever.
Why must I rinse my mouth after a combination inhaler?
Rinsing and spitting after each dose prevents oral thrush and hoarseness, the most common side effects of the steroid component.
Are combination inhalers interchangeable?
No. Doses, devices and instructions differ substantially between brands. Check with us before using an inhaler that looks different from your usual one.
How do I know my asthma is not controlled?
Needing a reliever three or more times a week, night waking, or symptoms limiting activity all mean control is not good enough. Book a review.

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