Is a cardioselective beta blocker safe for someone with mild asthma? it is to treat pots when standing.

Maybe: It's highly individualized and depends on the severity of your asthma and dose of the drug being used. Some people will tolerate it and some won't. Even those who do may have a worsening of their asthma following a respiratory infection months or years hence. You can always try it, stop it if necessary, and use a bronchodilator till back to baseline.