The young shoots were often collected in the spring by Native American people and mixed with other greens. As the plant matures the leaves become tough and somewhat bitter. The southeast Native Americans use the stems in this stage. They are peeled and eaten raw. When properly prepared soon after picking they are a good source of vitamin C and pro-vitamin A. The Dena’ina add fireweed to their dogs’ food. Fireweed is also a medicine of the Upper Inlet Dena’ina, who treat pus-filled boils or cuts by placing a piece of the raw stem on the afflicted area. This is said to draw the pus out of the cut or boil and prevents a cut with pus in it from healing over too quickly.
The root can be roasted after scraping off the outside, but often tastes bitter. To mitigate this, the root is collected before the plant flowers and the brown thread in the middle removed.
In Russia, its leaves are used as tea substitute and were exported, known in Western Europe as Koporye Tea(Копорский чай) or Russian Tea. Fireweed leaves can undergo fermentation, much like real tea. Today, koporye tea is still occasionally consumed though not commercially important.
Chamerion angustifolium (Epilobium angustifolium) herb has been used in the traditional Austrian medicine internally as tea for treatment of disorders of the prostate, kidneys, and urinary tract.