Perforomist Side Effects: What to Expect and When to Call Your Doctor

Perforomist (formoterol fumarate 20 mcg/2 mL inhalation solution) is generally well-tolerated when used as directed. Like all medications, however, it does have potential side effects — ranging from mild nuisances to rare but serious reactions that require immediate medical attention. This guide covers everything you need to know about Perforomist side effects in plain language.

Boxed Warning: What Perforomist's Most Important Warning Means

Perforomist carries the FDA's most serious type of warning — a

boxed warning — related to its use in asthma patients. This warning states that long-acting beta-agonists (LABAs) like formoterol, when used without an inhaled corticosteroid (ICS), increase the risk of asthma-related death.

This warning does NOT apply to COPD patients taking Perforomist as prescribed. Perforomist is FDA-approved for COPD, not asthma. If you have COPD and are taking Perforomist as directed, this boxed warning is not a concern for you — but it is why Perforomist should never be used for asthma.

Common Side Effects (Reported in Clinical Trials)

The following side effects occurred in at least 2% of patients taking Perforomist in clinical studies. Most are mild and often improve as your body adjusts:

• Tremor (shakiness): A common effect of beta-agonist medications; usually affects the hands and typically mild
• Headache: Usually mild and transient
• Nervousness or anxiety: Related to beta-adrenergic stimulation
• Nausea: Generally mild; less common with correct nebulizer use
• Dizziness: Sit or lie down if it occurs; do not drive until resolved
• Dry mouth: Rinse mouth after nebulization if bothersome
• Insomnia: Try taking your evening dose earlier if this is an issue
• Sore throat, cough, or stuffy nose: Upper respiratory tract irritation from inhaled medication
• Back pain, muscle cramps: Reported in clinical studies; generally mild

Serious Side Effects — Call Your Doctor Immediately

Contact your healthcare provider immediately — or call 911 in an emergency — if you experience any of the following:

• Paradoxical bronchospasm: Increased wheezing or difficulty breathing immediately after using Perforomist. Stop using it and use your rescue inhaler. This can be life-threatening.
• Fast or irregular heartbeat (palpitations): Formoterol can increase heart rate and affect cardiac rhythm. Report to your doctor.
• Chest pain or tightness: May indicate cardiovascular effects; seek immediate care
• Severe allergic reaction: Hives, difficulty breathing, swelling of the face, lips, tongue, or throat — call 911 immediately
• Low potassium signs: Leg cramps, constipation, numbness or tingling, muscle weakness, irregular heartbeat
• High blood sugar signs: Increased thirst, frequent urination (especially if you have diabetes)

Side Effects You Should NOT Be Concerned About

A slight increase in heart rate (5–10 beats per minute) after nebulization is a normal pharmacological effect of beta-agonist medications and is not cause for concern unless it's extreme or accompanied by chest pain. Similarly, mild hand tremors that appear shortly after nebulization and resolve within an hour are expected.

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Tips to Minimize Side Effects

• Use Perforomist exactly as prescribed — one 20 mcg vial twice daily. Do not exceed the recommended dose.
• Do not mix other medications in the nebulizer with Perforomist
• Rinse your mouth after nebulization to reduce throat irritation and dry mouth
• Report any bothersome or worsening side effects to your prescriber

When to Seek Emergency Care

Call 911 or go to the nearest emergency room if you experience: sudden severe difficulty breathing, chest pain radiating to the arm or jaw, loss of consciousness, severe swelling of the face or throat, or any symptoms that feel like a life-threatening emergency.

Also see our guide to

Perforomist drug interactions and

what Perforomist is used for.