What Are the Nebulizer Side Effects in Adults?

Nebulizers deliver medication as a fine mist you breathe in over several minutes, and while they are generally safe, they carry a distinct profile of side effects that depends heavily on which drug is in the cup. The most commonly nebulized medications in adults are short-acting beta-agonists like albuterol, anticholinergics like ipratropium bromide, inhaled corticosteroids, hypertonic saline, and inhaled antibiotics. Each drug class brings its own set of potential problems, and the nebulizer itself introduces a few concerns that other inhalers do not, from preservative reactions to bacterial contamination of the equipment.

Tremor, Racing Heart, and Jitteriness from Beta-Agonists

Albuterol (salbutamol) is by far the most frequently nebulized bronchodilator for adults with asthma or COPD, and its side effects are driven by the fact that beta-2 receptors exist beyond your lungs. The classic trio is tremor, a fast or pounding heartbeat, and a feeling of nervousness or restlessness. Tremor shows up in roughly two to four percent of patients taking regular beta-agonist therapy and is dose-related, meaning higher or more frequent nebulizer doses make it more likely.¹ The shaking tends to affect the hands most and comes from a direct effect on skeletal muscle rather than anything happening in the brain.²

Heart rate changes from nebulized albuterol are usually modest. In intensive care patients whose heart rates were normal at baseline, the average increase after a nebulized dose was about four to five beats per minute. In patients who already had a fast heart rate, the bump was even smaller and not statistically meaningful.³ That said, the reassurance of small average changes does not mean every individual is safe. Beta-agonists have inotropic and chronotropic effects on the heart and can, in vulnerable people, increase arrhythmias, worsen cardiac ischemia, or contribute to heart failure.⁴ The good news is that these side effects tend to diminish with continued use as the body develops tolerance.⁵

Potassium Drops and Blood Sugar Shifts

A side effect many adults are unaware of is that nebulized beta-agonists push potassium from the blood into cells, temporarily lowering your serum potassium. In a study of adults receiving frequently nebulized albuterol for asthma exacerbations, potassium fell from a baseline of about 4.1 to 3.5 within 90 minutes, and about one in five patients had potassium dip below 3.0 at some point during treatment.⁶ This effect is clinically significant because low potassium can provoke muscle cramps, weakness, and, at its worst, dangerous heart rhythms. Nebulized salbutamol lowered potassium by a similar amount in patients with chronic kidney disease, and the drop lasted at least three hours.⁷

The potassium-lowering effect matters most when you are already on medications that lower potassium themselves, like certain diuretics or high-dose corticosteroids. Blood glucose also tends to nudge upward after nebulized beta-agonists because the same adrenergic stimulation triggers insulin release and changes glucose handling.⁸ For most adults with normal kidneys and no diabetes, these metabolic shifts are transient and harmless. But for people managing diabetes or kidney disease, frequent nebulizer use calls for closer monitoring.

Oral Thrush and Voice Problems from Inhaled Steroids

Nebulized corticosteroids like budesonide are prescribed for persistent asthma and sometimes severe COPD. Their signature local side effect is oral and pharyngeal candidiasis, the white patches and soreness commonly called thrush. The incidence of clinical thrush with inhaled steroids runs up to about 13 percent when based on physical findings plus a positive culture, though positive Candida cultures without symptoms are found in up to half of patients using steroid inhalers.⁹ The reason is straightforward: corticosteroid residue settling in the mouth and throat suppresses local immune defenses, letting Candida overgrow.

Another frustrating side effect is dysphonia, a hoarseness or weakening of the voice caused by steroid deposits on the vocal cords. This can range from mild roughness to a voice so strained that it interferes with work and social life. Both thrush and dysphonia are manageable: rinsing your mouth thoroughly with water and spitting after each treatment clears residual drug from the oral cavity and meaningfully reduces the risk of both problems.

Interestingly, nebulized budesonide may produce less systemic absorption than the same drug delivered through a metered-dose inhaler. In healthy volunteers given high-dose budesonide, the nebulized form caused no significant suppression of morning cortisol, while the metered-dose inhaler and dry powder inhaler forms suppressed it by over 70 percent.¹⁰ A similar pattern showed up with beclomethasone: nebulized doses achieved lower peak blood levels and were absorbed more slowly compared to the same drug from a metered-dose inhaler.¹¹ This lower systemic exposure means nebulized corticosteroids may carry a somewhat smaller risk of whole-body steroid side effects compared to inhaler versions at equivalent labeled doses.

Adrenal Suppression with Long-Term Inhaled Steroids

Even though the systemic absorption of nebulized steroids can be lower, long-term use of any inhaled corticosteroid raises the possibility of adrenal suppression. Your adrenal glands normally produce cortisol, and even small amounts of exogenous steroid entering the bloodstream over months or years can dial down that natural production. If the drug is then stopped abruptly or the dose reduced sharply, the adrenals may not ramp back up fast enough, causing fatigue, dizziness, nausea, or in rare cases a life-threatening adrenal crisis.¹²

A large population-based study found that inhaled corticosteroid use roughly tripled the risk of adrenal insufficiency compared to nonuse, and that every additional 100 micrograms per day of inhaled corticosteroid was associated with a three percent increase in incidence.¹³ The absolute risk remains low for most adults on standard doses, but it climbs with higher daily doses and longer treatment duration. If you have been on nebulized steroids for months, tapering rather than stopping cold is the safer approach.

Anticholinergic Side Effects from Ipratropium

Ipratropium bromide is the other mainstay bronchodilator commonly delivered by nebulizer, often combined with albuterol. Its side effects stem from blocking acetylcholine receptors. The most common complaint is dry mouth, which can be annoying but is rarely dangerous. Less commonly, the anticholinergic action can slow the bladder muscle and cause urinary retention, particularly in men with enlarged prostates. A nested case-control study of over 22,000 patients with COPD found that those inhaling anticholinergic medications had a 40 percent higher risk of acute urinary retention compared to nonusers, with the risk highest among people who had recently started the medication.¹⁴

An unusual but well-documented risk is acute angle-closure glaucoma triggered when nebulized ipratropium escapes around the edges of a face mask and contacts the eyes. The pupil dilates from the local anticholinergic effect on the eye’s surface, and in someone with the right anatomical predisposition this can block fluid drainage and send eye pressure surging.¹⁵ This is not a systemic drug effect; it is a mechanical problem of mist leaking past a loose-fitting mask. Using a mouthpiece instead of a mask, or ensuring the mask fits snugly over the nose and mouth, virtually eliminates the risk.

The Preservative Problem

Some multi-dose bottles of albuterol nebulizer solution contain benzalkonium chloride (BAC) as a preservative. BAC itself can cause bronchoconstriction, which is the opposite of what the albuterol is supposed to do. The effect is dose-dependent and cumulative, meaning the first nebulized dose may be fine, but repeated doses over hours can push BAC past the threshold where it starts tightening the airways.¹⁶ Patients with more severe airway obstruction are the most vulnerable because their airways are already hyperresponsive.¹⁷

The practical takeaway: if you are using frequent nebulizer treatments during a severe asthma flare and feel like the albuterol is not working or your breathing is getting worse despite treatment, the preservative in the multi-dose bottle could be part of the problem. Unit-dose vials of albuterol are typically preservative-free and avoid this issue.¹⁸

Hypertonic Saline and Cough

Nebulized hypertonic saline, typically at concentrations of three to seven percent, is used in adults with bronchiectasis and cystic fibrosis to help loosen thick mucus. It works well for that purpose, but the concentrated salt solution irritates the airways. Many patients report cough, throat irritation, shortness of breath, and a salty taste during or immediately after the treatment.¹⁹ Most clinicians have patients inhale a bronchodilator before hypertonic saline to pre-open the airways and reduce the bronchoconstriction that the salt can trigger. The side effects are usually tolerable once patients find the concentration and pre-treatment routine that works for them, but a small number of adults simply cannot tolerate hypertonic saline at any strength.

Dirty Equipment and Infection Risk

A side effect unique to nebulizers compared to inhalers is the infection risk that comes from the device itself. Nebulizer cups, tubing, and masks provide warm, moist surfaces that bacteria love. Research has shown that home nebulizers are frequently contaminated with pathogenic bacteria, and those organisms can detach from the surface and become aerosolized during treatment, meaning you breathe them directly into your lungs.²⁰ The risk is highest when nebulizers are dried or stored in humid environments. For adults with chronic lung diseases like COPD or bronchiectasis, whose lungs are already prone to infection, a contaminated nebulizer is a meaningful hazard.

Cleaning protocols vary by manufacturer, but the basics apply to everyone: wash the nebulizer cup in warm soapy water after each use, rinse it, and let it air dry completely. Many respiratory therapists recommend disinfecting the cup daily, either by soaking in a dilute vinegar solution or using the method specified in the device manual. Replacing the nebulizer cup and tubing on a regular schedule, often every few months, also reduces bacterial buildup.

Why Older Adults Face Higher Risks

Adults over 65 are more susceptible to nearly every nebulizer side effect, and for several overlapping reasons. Age-related changes in how the body metabolizes drugs mean the same nebulized dose can produce higher effective concentrations. Cardiovascular disease is common in this age group, so the cardiac effects of beta-agonists, particularly the potential to provoke arrhythmias or worsen ischemia, carry more clinical weight.²¹ Older adults are also more likely to be on multiple medications, creating opportunities for drug-drug interactions. A diuretic that already lowers potassium combined with frequent nebulized albuterol that also lowers potassium can push levels into a dangerous range faster than either drug alone.

The glaucoma risk from ipratropium mist leaking around a face mask is also more pronounced in older adults, both because the anatomical predisposition to angle-closure glaucoma is more common with age and because loose-fitting masks are more likely when facial contours change. Using a mouthpiece rather than a mask is strongly preferred in any adult who can manage it, and is especially worth insisting on in older patients.²²

Reducing Side Effects in Practice

Many nebulizer side effects are avoidable or at least manageable with practical adjustments. The choice of device and interface matters: a mouthpiece delivers medication more efficiently to the lungs and eliminates the ocular exposure risk that comes with face masks. For adults who cannot hold or manage a mouthpiece, a well-fitting aerosol mask is the next best option.²³

A few other steps that make a real difference:

Mouth rinsing: After nebulized corticosteroids, rinsing and spitting reduces drug residue on the oral and pharyngeal surfaces, cutting the risk of thrush and hoarseness.
Preservative-free vials: Unit-dose albuterol avoids the cumulative bronchoconstriction risk from benzalkonium chloride in multi-dose bottles.
Pre-bronchodilator for saline: Inhaling a beta-agonist before hypertonic saline opens the airways and blunts the cough and tightness that concentrated salt triggers.
Regular equipment cleaning: Washing and thoroughly drying the nebulizer cup after each use, and replacing disposable components on schedule, minimizes bacterial contamination.
Gradual tapering: If you have been on nebulized steroids for an extended period, reducing the dose gradually rather than stopping abruptly protects against adrenal insufficiency.

Nebulizing Unauthorized Substances

A trend that gained traction during the COVID-19 pandemic was people nebulizing substances never intended for inhalation, most notably hydrogen peroxide. One documented case involved a man who mixed hydrogen peroxide with distilled water and ran it through his CPAP humidifier nightly in an attempt to prevent COVID. Within a week he developed acute chemical pneumonitis, with chest imaging showing widespread lung consolidation, fluid, and bilateral pleural effusions.²⁴ Hydrogen peroxide is a potent oxidizer that, when inhaled as a mist, causes direct chemical burns to the airway lining and lung tissue.

Similar reports exist for people nebulizing colloidal silver, essential oils, and various homemade solutions. A nebulizer is designed to deliver pharmaceutical-grade preparations that have been formulated and tested for inhalation safety. The lungs are extraordinarily sensitive to irritants, and substances that seem harmless when swallowed or applied to skin can cause severe damage when aerosolized deep into the airways. If a substance was not prescribed specifically for nebulized delivery, putting it in a nebulizer cup is a gamble with high stakes and no proven benefit.