No rule for this one
No ending or word group predicts the article of Husten. Learn it as a pair and say it out loud: der Husten.
der Husten
It's der Husten. Husten is masculine.
Ich habe Husten.
I have a cough.
No ending or word group predicts the article of Husten. Learn it as a pair and say it out loud: der Husten.