Does Poison Spell deal damage to own units in its radius?

As in question title, does Poison Spell deal damage to own (attacker's) units under its radius, or only to enemy units? The description says "Defending units" but I want to make sure :)

No. The spell will only deal damage to enemy units.

From the clash of clans wiki:

It does damage and slows down all enemy Troops, Heroes, and Skeletons inside its area of effect, but does not deal damage to buildings.

It only does damage to enemy units. By defending units, it means any troops in the defenders clan castle (it also affects enemy heroes). Thus, you can drop a poison spell on top of your troops and it won't effect them.

read more about it here