Can my 9yr old take benzonatate for his persistent cough?

No! It is approved for use in only adults and children 10 and older by the FDA in the US. There are many precautions for use of this drug, so even in adults it is best to consult your pharmacist or doctor before using it.

There was a serious warning posted by The Medical Letter about an FDA warning on this Tessalon, Tessalon Perles, aka benzonatate. See below in the related links section for a link to this warning.

In Brief: Benzonatate Warning

The Medical Letter on Drugs and Therapeutics • February 7, 2011 (Issue 1357) p. 9

The FDA recently warned that accidental ingestion of the antitussive benzonatate (Tessalon Perles, and others) by children less than 10 years old can be fatal. This widely prescribed oral agent, which has been available in the US since 1958, can also cause severe morbidity and death in older children and adults, and not only in overdosage.

Benzonatate is a polyglycol derivative structurally related to procaine and tetracaine. It acts peripherally on stretch receptors in the lower respiratory tract to suppress the cough reflex. If the patient chews or sucks the liquid-filled capsules or "softgels", the drug can cause laryngospasm, bronchospasm and circulatory collapse. Adverse effects that can occur after swallowing an intact capsule include a feeling of numbness in the chest, mental confusion, a sensation of burning in the eyes, and visual hallucinations.

Taken in overdose, benzonatate can rapidly cause seizures, cardiac arrhythmias and death. Serious adverse outcomes reported to the National Poison Center between 2000 and 2006 occurred in 116 patients (41 in children <6 years old), with 4 deaths. The 5 children known to the FDA who died from benzonatate ingestion were ≤2 years old and some apparently took only one or two capsules. In one well-documented case report, a 17-year-old girl who intentionally took 10 or more 200-mg capsules developed seizures, cardiac arrest from which she was resuscitated, and then blindness, which persisted. When a cough suppressant is truly necessary, dextromethorphan or even codeine might be a safer choice.