Castlevania: Circle of the Moon/Items

Potions
These items restore a certain number of hit points when used. Basic potions restore very little, even in the beginning of the game, so try and keep a stockpile of 5 on you at all time and save them for boss fights. Latter in the game, Fox Hunters and Imps are easy to find, so keep fighting them until you get a decent supply of meat.

Mind Restores
These work just like potions, except they restore a percentage of MP. They are generally much harder to find than potions and meat, so use them sparingly. You may be better off standing around an empty room for a few minuets until your MP restores itself than using up an item. Brain Floats are fairly common early in the game and reappear as soon as you leave the screen (not necessarily the room), so keep killing them.

Hearts
While the hearts that you find in candles (small and large) have to be used instantly, there are heart items that can be used to restore hearts at any point. Unfortunately they are much rarer than potions or even mind restores. Save them for boss fights instead of just using them to save time running around smashing candles.

Note that the Venus/Manticore combo doubles the number of hearts gained only when picking up small and large hearts - not when using one of the items.

Status Restorers
Status effects (Poison, Petrified, and Cursed) all wear off on their own, however you can suffer a lot of damage from the effects in the mean time. These items restore you instantly, though they do no restore HP that was already lost. If you don't mind cheating a little bit, there is an exploitable glitch that can do this for free.

Power-ups
These are hidden items that permanently increase the amount of HP, MP, or Heart that you have. They are used instantly by touching them. HP Pluses and MP Pluses will also fully restore your HP or MP upon contact, though a Heart Plus will not recover missing hearts.

By collecting all of these items you gain an additional 430HP, 360MP, and 216 Hearts. Depending on what mode you're playing through and what level you end the game at, power-ups can account for one third to one half of your total stats.