If any of these effects persist or worsen, tell your doctor or pharmacist promptly. Buy Ventolin (Aurosal) Asthma 200mcg Online Australia Do not increase your dose or use it more frequently than prescribed without your doctor's approval.If you are using this medication to prevent asthma brought on by exercise, inhale 2 puffs 15 to 30 minutes before exercise or as directed by your doctor.If you find it difficult to use this inhaler correctly, it may help to use a spacer device with this inhaler.