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

Serevent Diskus (salmeterol xinafoate) is a long-acting beta-2 agonist (LABA) inhaler used to manage asthma and COPD. Like all medications, it can cause side effects — most are mild and manageable, but some are serious. Understanding what to expect, what to watch for, and when to seek immediate care is essential for any Serevent patient.

The Most Important Warning: Serevent's Black Box on Asthma-Related Death

Before listing side effects, it's critical to understand Serevent's FDA black box warning — the strongest safety alert the FDA requires. Long-acting beta-2 agonists (LABAs) like salmeterol increase the risk of asthma-related death when used WITHOUT an inhaled corticosteroid (ICS).

The Salmeterol Multicenter Asthma Research Trial (SMART) found 13 asthma-related deaths in 13,176 patients taking salmeterol over 28 weeks, compared to only 3 deaths in 13,179 placebo patients. This risk appears highest in African-American patients.

What this means for you: If you're using Serevent for asthma, you must also be using a separate inhaled corticosteroid. Never use Serevent alone as the only asthma medication. Your doctor should have prescribed both. For COPD patients, Serevent can be used without an ICS, as the black box warning applies specifically to asthma monotherapy.

Common Side Effects of Serevent Diskus

These side effects are reported by patients in clinical trials and are generally mild. They often improve as your body adjusts to the medication:

Headache: One of the most commonly reported side effects. Usually mild and often resolves with continued use.

Pharyngitis (sore throat): Throat irritation from the inhaled powder. Rinsing your mouth and gargling after each use can help.

Rhinitis (stuffy or runny nose): Nasal inflammation or upper respiratory congestion.

Tremor: Mild shaking or trembling, especially of the hands. This is a class effect of beta-2 agonists and typically mild at recommended doses.

Palpitations: Awareness of a rapid or irregular heartbeat. Usually mild at therapeutic doses, but see your doctor if persistent or concerning.

Cough: Some patients experience cough with inhaled medications. This may be related to the inhaler powder.

Nausea, diarrhea: Gastrointestinal symptoms are less common but reported in clinical trials.

Muscle cramps: Some patients report muscle cramping, particularly in the legs.

Serious Side Effects — Seek Immediate Medical Attention

Contact your doctor immediately or call 911 if you experience any of the following:

Paradoxical bronchospasm: Serevent can, rarely, cause wheezing and breathing to worsen immediately after inhalation — the opposite of the intended effect. Stop Serevent immediately and use a rescue inhaler (albuterol). This is a medical emergency. Call 911 if breathing does not improve quickly.

Worsening asthma or breathing: If you are using your rescue inhaler more often or your breathing is getting worse despite using Serevent, contact your doctor immediately. Increasing rescue inhaler use is a sign of deteriorating asthma control.

Chest pain or rapid/irregular heartbeat: At therapeutic doses this is uncommon, but significant QTc prolongation can occur with overdose. Seek immediate care for chest pain, very fast heartbeat, or feeling of fainting.

Allergic reactions: Signs include rash, hives, swelling of the face/lips/tongue/throat, or difficulty breathing. Note: Serevent Diskus contains milk proteins (lactose). Patients with severe milk protein allergy should not use this inhaler.

Low potassium (hypokalemia): Beta-2 agonists can drive potassium into cells, lowering blood levels. Symptoms include muscle weakness, cramping, or irregular heartbeat — particularly relevant for patients on diuretics.

Important Usage Reminders to Avoid Side Effects

Never use more than 1 inhalation twice daily. Exceeding the dose dramatically increases cardiovascular risk.

Serevent is NOT a rescue inhaler. Never use it for sudden breathing problems.

Rinse your mouth after use to reduce throat irritation.

Do not use Serevent if you are already taking another LABA (e.g., formoterol, vilanterol).

For information on drug interactions that can worsen Serevent side effects, see our guide: Serevent Drug Interactions: What to Avoid. And if you need help finding Serevent at a pharmacy near you, medfinder can help.