Which OTC anti-snoring products really work?

Oral appliance. The only otc product likely to work are jaw advancement oral mouthpieces. These act like prescription devices to create more air space in the back of the throat. They are not very adjustable however and can cause dental and TMJ problems.
None really. If you go and purchase an anti-snoring device otc or on the web, you may be jeopardizing your health. These products may seem to work, but the mouthpieces are non- adjustible and the other products may mask a more alarming form of sleep apnea. You should consider seeing your doctor for a sleep study and then get options- cpap, custom made oral appliance, surgery, lifestyle changes, etc.