Methacholine Side Effects

Medically reviewed by Drugs.com. Last updated on Apr 6, 2025.

Applies to methacholine: inhalation powder for solution, inhalation solution.

Important warnings This medicine can cause some serious health issues

Inhalation, oral/nebulization route (powder for solution)

Severe bronchoconstriction can result from methacholine chloride administration (including the lowest dose).

Use of methacholine chloride is contraindicated in pediatric and adult patients with baseline FEV1 less than 60% predicted or adults with FEV1 less than 1.5 L.

Use of methacholine chloride is not recommended in patients with clinically apparent asthma or wheezing.

If severe bronchoconstriction occurs, reverse immediately with a rapid-acting inhaled bronchodilator agent (beta-agonist).

Common side effects of methacholine

Some side effects of methacholine may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects.

Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

Less common side effects

• headache
• itching
• lightheadedness
• throat irritation

Serious side effects of methacholine

Along with its needed effects, methacholine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor or nurse immediately if any of the following side effects occur while taking methacholine:

Incidence not known

• cough
• difficulty breathing
• noisy breathing
• tightness in the chest

For healthcare professionals

Applies to methacholine: compounding powder, inhalation powder for reconstitution, inhalation solution.

General adverse events

When administered orally or by injection, this drug is reported to cause nausea, vomiting, substernal pain or pressure, hypotension, fainting, and transient complete heart block. Overdosage with this drug, when administered orally or by injection, can result in a syncopal reaction with cardiac arrest and loss of consciousness.^[Ref]

Dermatologic

• Rare (0.01% to 0.1%): Itching^[Ref]

Nervous system

• Rare (0.01% to 0.1%): Headache, dizziness
• Frequency not reported: Light-headedness^[Ref]

Respiratory

• Rare (0.01% to 0.1%): Throat irritation
• Frequency not reported: Bronchospasm (includes symptoms such as chest tightness, cough or wheezing)^[Ref]

Further information

Methacholine side effects can vary depending on the individual. Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Note: Medication side effects may be underreported. If you are experiencing side effects that are not listed, submit a report to the FDA by following this guide.

Medical Disclaimer