“When should you go to the ER for shortness of breath relating to covid-19?”

When your pulse oximeter is less than 94%.

Shortness of breath is the major symptom criteria to visit your nearest hospital.

If you are feeling shortness of breath and concerned about COVID 19 infection, see if you can walk around your house or up the stairs to see how long it takes you to recover. If you can walk 100 meters/330 feet and do not need an extended period of time to recover, you likely can wait on going to the emergency department. Taking into account your baseline ability to walk 100 meters/330 feet in that if you normally can only make it 20 meters/22 feet, then use that distance.

If you are still not certain after trying mild exertion, you can call an ambulance to check your pulse oximetry (blood oxygen level). You can also use a portable device to check your oxygen level, as well. If you are using a portable device, make sure your hand is warm enough to pick up a correct reading.

You should seek immediate medical care whenever you are short of breath, whether it is due to Covid or not. Until a medical provider examines you, checks your oxygen saturation, and considers whether you need a chest X-ray, you are simply guessing. I am very concerned people could wait too long and suffer permanent disability or death by delaying seeking needed medical care. And many patients assume they have Covid, when they end up having a life-threatening condition that could be treated (like pneumonia, blood clot in their lung, etc.).

Exactly then. When you are short of breath.

I would recommend going to the ER ASAP for evaluation. Especially if your shortness of breath has continued to progress.