The guidance includes taking cover quickly in a concrete structure, preferably underground.
The factsheet, issued by Guam’s Office of Civil Defence and titled Preparing for an Imminent Missile Threat, advises people not to look at the flash of a fireball because it could cause blindness.
It also includes guidance on removing radioactive material, saying: “When possible, take a shower with lots of soap and water to help remove radioactive contamination.
“But don’t scratch or scrub skin and do not use conditioner in your hair because it will bind radioactive material to your hair.”
Officials have not raised the US territory’s threat level after Pyongyang said it had laid out plans to strike near the island in the coming weeks.
President Donald Trump has issued a number of warnings to the rogue state over its threats to the US and on Friday said leader Kim Jong Un will “truly regret an attack on Guam”.
Guam governor Eddie Calvo said the territory has many buildings made to withstand powerful typhoons, yet he acknowledged that nothing can protect against a nuclear attack.
President Trump assured Mr Calvo that Guam is safe during a phone call. He said: “We are with you a thousand percent. You are safe.”
The distribution of the factsheets did not appear to cause anxiety but some people went in search of plastic sheeting after the guidance recommended using duct tape and plastic sheeting “to seal all cracks around the door and any vents into the room”.