"Do not use conditioner in your hair because it will bind radioactive material to your hair", it continues.
North Korea on Thursday announced a detailed plan to launch a volley of ballistic missiles toward the U.S. Pacific territory of Guam, a major military hub and home to U.S. bombers.
The guidance includes taking cover quickly in a concrete structure, preferably underground.
Mr Trump has said he would respond to any such action with "fire and fury".
The U.S. dollar inched up against the Japanese yen and the Swiss Franc on Friday, erasing earlier losses, after Russian Foreign Minster Sergei Lavrov said there was a Russian-Chinese plan to defuse tensions between the United States and North Korea. Guam officials are disseminating fact sheets to help residents prepare for a possible missile attack from North Korea. "I'm working with Homeland Security, the rear admiral and the United States to ensure our safety, and I want to reassure the people of Guam that now there is no threat to our island or the Marianas".
Officials have not raised the U.S. territory's threat level after Pyongyang said it had laid out plans to strike near the island in the coming weeks.
Guam Homeland Security and Office of Civil Defense released a two-page fact sheet on social media and its website.
The exchange capped a week of escalating warnings between Washington and Pyongyang.
The island houses about 7,000 US troops spread between Andersen Air Force base and Naval Base Guam.
The fact sheet, first reported Friday by the Pacific Daily News, explains that brick or concrete structures are the safest places to shelter from nuclear fallout, and that those with thick walls and roofs best absorb radioactive particles. But officials in Guam, the tiny island territory that Kim Jong Un has threatened to attack, aren't keeping citizens in the dark.
Those who can't get indoors or behind some type of protections should simply lie down and cover their heads.
Showering is equally important, while "lots of soap and water" must be used to help remove radioactive materials.