Fostair Side Effects: Complete Safety Guide

Common and Uncommon Side Effects of Fostair

Based on the Patient Information Leaflet (PIL) and clinical trials, side effects are categorised by frequency.

Common (affecting up to 1 in 10 people)

• Fungal infections of the mouth and throat (oral candidiasis) – whitish patches, soreness.
• Hoarseness (dysphonia) and sore throat.
• Headache.
• Pneumonia in patients with COPD (tell your doctor if you have fever, increased sputum, worsened cough).
• Palpitations and fine tremor (usually mild and often improve with continued use).

Uncommon (affecting up to 1 in 100 people)

• Rapid or irregular heartbeat (tachycardia, atrial fibrillation).
• Muscle cramps, agitation, restlessness, dizziness.
• Nausea, taste disturbances.
• Increase in blood glucose or decrease in serum potassium.

Rare / Very rare (affecting less than 1 in 1,000)

• Paradoxical bronchospasm (sudden worsening of breathing after use).
• Hypersensitivity reactions (rash, itching, angioedema).
• Adrenal suppression, Cushing’s syndrome (with high doses/long-term use).
• Glaucoma, cataracts, growth retardation in children (not licensed for under 18).

When Do Fostair Side Effects Start? (Onset Timeline)

The onset varies by type of effect:

• Immediate (minutes to hours): paradoxical bronchospasm, palpitations, fine tremor, headache – can occur after the first dose or at any time. These are usually due to formoterol’s beta‑agonist activity.
• Early (days to weeks): oral thrush, hoarseness – develop with regular use if mouth not rinsed. They indicate local corticosteroid deposition.
• Delayed (weeks to months/years): systemic corticosteroid effects like adrenal suppression, glaucoma, cataracts – only with prolonged high‑dose use. Growth retardation would only apply to children (Fostair not licensed in paediatrics).

Most people using Fostair at recommended doses experience few, if any, side effects. Those that occur are often mild and transient.

How Long Do Fostair Side Effects Last? (Duration)

• Palpitations, tremor, headache: usually last 1‑2 hours after each dose and often diminish after the first week as your body adjusts.
• Oral thrush: can persist if untreated. It usually resolves within a few days of using antifungal treatment and improving inhaler technique (rinsing mouth).
• Hoarseness: often reversible within days after stopping or using a spacer.
• Systemic effects (adrenal suppression): may take weeks to months to fully recover after stopping high‑dose therapy; gradual dose reduction under medical supervision is needed.
• Allergic reactions: resolve upon discontinuation; antihistamines or steroids may be required.

If side effects persist or worry you, consult your doctor. Do not stop Fostair abruptly without advice.

Contraindications: Who Should Not Use Fostair

Fostair is contraindicated in the following situations (based on PIL section 2):

• Allergy to beclometasone dipropionate, formoterol fumarate, or any excipient (ethanol, norflurane).
• Children and adolescents under 18 years (safety not established).
• Do not use as a rescue inhaler for acute asthma attacks unless you are on the MART regimen and your doctor has specifically instructed you.

Warnings – use with caution and only after medical assessment:

• Heart conditions: recent heart attack, angina, heart failure, severe hypertension, arrhythmias, long QT syndrome.
• Thyrotoxicosis (overactive thyroid).
• Phaeochromocytoma (tumour of the adrenal gland).
• Diabetes (formoterol may increase blood glucose).
• Hypokalaemia (low potassium).
• Severe liver or kidney disease.
• If you are due to have anaesthesia (may need to stop 12 hours before).

Food and Drug Interactions with Fostair

Food interactions

There are no known interactions with food. However, you should rinse your mouth with water after each use – this is not related to food but to prevent oral thrush. The small amount of ethanol in each puff is negligible and does not interact with food.

Drug interactions (from PIL section 2)

• Beta‑blockers (e.g., atenolol, propranolol, sotalol, timolol eye drops) – may reduce or block formoterol’s effect. Avoid concomitant use.
• Other beta‑adrenergic drugs – may increase formoterol effects (tremor, palpitations).
• Medicines that can cause low potassium: diuretics, theophylline, aminophylline, steroids – increased risk of hypokalaemia, especially in severe asthma.
• MAO inhibitors, tricyclic antidepressants, phenothiazines – may increase cardiovascular side effects (QT prolongation, arrhythmias).
• HIV protease inhibitors (ritonavir, cobicistat) – can increase systemic exposure to beclometasone; monitor for corticosteroid side effects.
• Drugs that can prolong QT interval (e.g., quinidine, procainamide, some antihistamines) – use with caution.
• Anaesthetics – risk of arrhythmias; inform your anaesthetist you use Fostair.

Serious Side Effects and When to Seek Help

Although rare, the following require immediate medical attention:

• Paradoxical bronchospasm: sudden worsening of breathing, wheezing immediately after a puff. Stop Fostair, use your blue reliever, and seek urgent advice.
• Allergic reactions: skin rash, itching, swelling of face/lips/throat, difficulty swallowing.
• Signs of adrenal insufficiency: severe weakness, fatigue, nausea, vomiting, low blood pressure – especially after long‑term high doses or during stress (infection, surgery).
• Chest pain or palpitations with fainting – possible arrhythmia.
• Blurred vision or eye pain – possible glaucoma or cataract.

If you experience any of these, stop using Fostair and contact your doctor immediately or go to A&E.

Fostair FAQs: Side Effects

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