Using the idclev cheat code to warp to a level has the following side effects:
- The player's status is reset to that of a newly launched game. That is, 100 percent health, no armor, the pistol in hand, and 50 bullets. This naturally deactivates any other powerups still in effect and eliminates any keys or weapons previously acquired, whether obtained using cheat codes or otherwise.
- If the second digit of the level number warped to is 1 (and if typed quickly in succession, even if the first digit is 1), the player will switch to the fist upon entering the new level.
- The -respawn and -nomonsters parameters are ignored, if either was used when originally launching the game.
- If fast monsters were being used before warping on a skill level other than "Nightmare!", their attack frequency reverts to normal, although the increased speed of demons, spectres, and certain projectile attacks remains the same.
- If activated while the menu system is being used (by pressing idclev, the Esc key, and then the level numbers), only half the screen will be updated. The other half will continue to display a view of the old level until the menus are exited. Another way to cause the same effect without the use of idclev is to press the Esc key and to tap the Enter key two or three times and repeat the same sequence before the screen melt is finished.
- Typing IDCLEV## with a number higher than 32 (Or higher than 33 if you have the Doom 3: BFG Edition of Doom 2) and lower than 41 will crash the game.
- While playing the shareware version, if the player tries to warp to a level that is only available in the registered version, they will instead be warped to the corresponding shareware level. For example, if attempting to warp to E3M5, the player will instead be warped to E1M5.