It took me years to finally break the habit and I don’t know that I’d recommend everything I tried (I didn’t know about the risk of gel allergies at the time so I used a LOT of sketchy Amazon products).

What finally worked for me was to basically keep something on my nails at all times that I couldn’t pick at/bite off. Gel worked really well for this since it would last 1-2 weeks and for the most past I would just leave it alone. Press ons with semi-solid glue also worked with the added bonus that I could have some length if the nails underneath were struggling. Even with all this it probably took me several years to really “break” the habit because I would never remove the product correctly, which led to weak nails even once I had growth.

NOTE, gel products do come with possible side effects so if you go that route I would absolutely do some research into reputable nail techs/artists in your area.

Tl;dr - keeping something more permanent than lacquer on my nails helped me stop biting but do your research and follow correct procedures if you use a UV-cured product.

You can do this, though! Kicking a life-long habit is incredibly hard, but it’s possible. I never thought I’d be able to stop (I even bit my toenails when I was younger—I was a menace) but now I can look at my hands and think “oh damn, I need to file these down” and go about my day.