From the Guidelines
Benzonatate can cause several side effects, including common effects like drowsiness, dizziness, and temporary numbness in the mouth or throat, as well as more serious but less common effects like confusion, hallucinations, and severe allergic reactions, as noted in studies such as 1 and 1.
Common Side Effects
- Drowsiness
- Dizziness
- Headache
- Mild nausea
- Constipation
- Temporary numbness in the mouth or throat
Serious Side Effects
- Confusion
- Hallucinations
- Severe allergic reactions (rash, itching, swelling, severe dizziness, trouble breathing)
- Seizures
Important Considerations
- Benzonatate works by numbing stretch receptors in the lungs to suppress cough reflexes, which can lead to throat numbness as a side effect.
- The standard dosage is typically 100-200 mg three times daily, not to exceed 600 mg per day.
- Patients should never chew or crush the capsules, as this can cause serious adverse effects, including throat numbness, choking, or other severe reactions, as highlighted in the context of managing cough in lung cancer patients 1.
- The medication should be swallowed whole with water, and if persistent or severe side effects occur, patients should contact their healthcare provider immediately.
- Benzonatate should be kept away from children, as even a single capsule can be fatal if chewed or sucked on, emphasizing the need for careful handling and storage.
Clinical Guidance
Given the potential for both common and serious side effects, it is crucial for healthcare providers to closely monitor patients taking benzonatate, especially in vulnerable populations such as the elderly or those with a history of respiratory conditions, as suggested by the expert panel report 1. Additionally, patient education on the proper use of benzonatate, recognition of side effects, and the importance of seeking medical attention if severe reactions occur is paramount for safe and effective management of cough symptoms.
From the FDA Drug Label
ADVERSE REACTIONS Potential Adverse Reactions to BENZONATATE may include: Hypersensitivity reactions including bronchospasm, laryngospasm, cardiovascular collapse possibly related to local anesthesia from chewing or sucking the capsule. CNS: sedation; headache; dizziness; mental confusion; visual hallucinations. GI: constipation; nausea; GI upset. Dermatologic: pruritus; skin eruptions. Other: nasal congestion; sensation of burning in the eyes; vague "chilly" sensation; numbness of the chest; hypersensitivity. WARNINGS Hypersensitivity Severe hypersensitivity reactions (including bronchospasm, laryngospasm and cardiovascular collapse) have been reported which are possibly related to local anesthesia from sucking or chewing the capsule instead of swallowing it.
The side effects of benzonatate may include:
- Hypersensitivity reactions: bronchospasm, laryngospasm, cardiovascular collapse
- CNS effects: sedation, headache, dizziness, mental confusion, visual hallucinations
- GI effects: constipation, nausea, GI upset
- Dermatologic effects: pruritus, skin eruptions
- Other effects: nasal congestion, sensation of burning in the eyes, vague "chilly" sensation, numbness of the chest, hypersensitivity 2 2
From the Research
Benzonatate Side Effects
- Benzonatate can cause severe side effects, including seizures, cardiac arrest, coma, brain edema, apnea, tachycardia, and respiratory arrest, especially in cases of overdose 3, 4.
- The onset of toxicity can be rapid, occurring within 15 minutes of ingestion 3 or less than 5 minutes 4.
- Most common symptoms of benzonatate overdose include cardiac arrest, seizures, and dysrhythmias 4.
- Treatments for benzonatate overdose are generally supportive in nature and may include intubation, cardiopulmonary resuscitation, and vasopressors 4.
- Benzonatate exposure can be fatal, especially in children, with 20 out of 31 reported overdose cases resulting in fatal outcomes 3.
- Pediatric benzonatate prescription utilization has increased, but remains low compared to other antitussive medications, with most exposure cases involving unintentional ingestion in children 0 to 5 years old 5.
- Benzonatate can also worsen asthma in some patients due to its benzoate content 6.
- In some cases, benzonatate has been used to treat opioid-resistant cough in advanced cancer patients, providing symptomatic relief 7.