Is it safe to use hydroquinone long-term? June 12, 2020 04:47 Updated There have been no reported incidents of topical hydroquinone causing cancer in humans. It is safe to use under doctor supervision. Click here to check out a hydroquinone safety Tip. Related articles What is hydroquinone? Do the dark spots come back if you stop using The Spot Cream? Do I need to avoid any ingredients? What is tretinoin? Are there any possible side effects?