Possible Side Effects Proventil
Most people do not have any problems when taking this medicine.* Some people may feel a bit shaky or have a headache.* Some people who are unusually sensitive may notice that their heart is beating faster and/or more forcefully than usual. This awareness of their heart beating is called palpitations, is normally harmless, and usually passes off as treatment continues. Some might notice that their heartbeat becomes uneven or their heart gives an extra beat. Tell your doctor as soon as possible, but do not stop using this medicine unless told to do so.* Mouth or throat irritation sometimes occurs with inhaled Proventil.* Muscle cramps have also been reported, although uncommon.* Very rarely Proventil may cause allergic reactions.* Proventil may affect the salt balance of the body, although this is rare.* Patients taking this medicine may become restless or excitable although this is very rare.If you feel unwell or notice anything unusual or which you do not understand, tell your doctor as soon as possible.

Drug Class and Mechanism Proventil
Proventil contains the active ingredient Salbutamol, which is a type of medicine known as a short-acting beta 2 agonist. It works by acting on receptors in the lungs called beta 2 receptors. Stimulation of these receptors causes the muscles in the airways to relax, allowing the airways to open.

More InformationProventil here
Proventil should not be taken with beta-blockers, such as atenolol, propranolol or timolol. This is because beta-blockers have an opposite action to this medicine and cause the airways to narrow. This can result in breathing difficulties for people with asthma or COPD. This problem has sometimes been seen with eye drops containing beta-blockers, eg. used for glaucoma.