Opt for these strips

Strips are the go-to when you have just 14 days to whiten—it takes them exactly that long to reach their potential. But the high concentration of bleach can trigger gum irritation and tooth sensitivity. To the rescue: Lumineux Oral Essentials Whitening Strips (OralEssentials.com), made with coconut oil (it pulls out embedded stains) and sea salt (it strengthens enamel to thwart new discoloration). And one study found that strips made with natural ingredients are as effective in whitening teeth as their harsh peroxide counterparts, sans the pain!