Encourage your friend to seek professional help. Even though household products like glue and air freshener have legal, useful purposes, when they are used as inhalants they are harmful and dangerous. These products are not intended to be inhaled. Or the 10th. Or the 100th.
Every huff can be dangerous.
Even if you have huffed before without experiencing a problem, there's no way of knowing how the next huff will affect you. Inhalants affect your brain and can cause you to suddenly engage in violent, or even deadly, behavior. You could hurt yourself or the people you love. The longer you ignore the real facts, the more chances you take with your life. It's never too late.