When must I start to go to the emergency room for an asthma attack?

No relief w/ meds. If you use your rescue medication and are not relieved or you need to use several times to get relief, you may need to be seen by your doctor or go to the er. Asthma always gets worse at night, so don't delay if you are having problems.
ER... You should seek emergent care for your asthma if your symptoms are worsening despite home therapy. If your attack is worse than usual, go to the er immediately. If you see a bluish color to your lips or fingers, get to the er. If you are unsure what to do, go to the er. Asthma exacerbation can be life-threatening so don't hesitate to seek help in the er for treatment during an attack!