Drug manufacturing companies GlaxoSmithKline and Alphapharm, in consultation with the Therapeutic Goods Administration (TGA), are voluntarily recalling several batches of Ventolin and Asmol inhalers due to a fault in the delivery mechanism of a small number of inhalers in each batch.

This can lead to less than the full dose being delivered for each puff.

The companies estimate about 25,000 to 50,000 inhalers from affected batches are involved in the recall, out of approximately 900,000 puffers distributed each month.

However, a TGA spokeswoman said users shouldn't be alarmed.

"At the same time they need to be aware that there is a possibility that their asthma relievers may not be supplying the correct dosage in each puff," she said.

"If relief is not obtained after taking the normal dose, consumers should take an additional one to two puffs to be on the safe side."

Anyone who continues to have difficulty breathing should contact their doctor for assistance.

The only Ventolin batch numbers affected are KN7170, KN7173, KN7178, and KN7179, whilst the Asmol batch numbers involved in the recall are KL6790, KL6795, KL6796, KL6797, KL6798, and KL6799.

Those with an inhaler from an affected batch can may return it to their pharmacy for replacement.