Is it permissible for a husband to take sexual stimulants without his wife's knowledge, and is it forbidden for him not to inform her?

The husband is not religiously obligated to inform his wife when using sexual stimulants, and there is no harm upon him if he does not inform her. However, he is not permitted to have intercourse with her in a way that harms her, and if she is harmed, she is not obligated to respond to his request.