How long is it safe to hold in a smoked hit of methamphetamine?

Answer 1

It is never safe to smoke methamphetamine.

Having said that hold it for as long as comfortable. You still need to breath after all. There will always be anecdotal evidence of someone having a heart attack or the like. Chances are they would have had one anyways. If you do have a heart condition you would be crazy to do any drugs which raise your heart rate. Think about it this way methamphetamine is water soluble and there is a ton of water in your lungs. You should notice that if you hold it for a short time say 10-15 sec then you will exhale less visible smoke. Alternatively you can shotgun it to the person you are smoking with as you should never do drugs alone.