Search the indicated locations to find all four Steroid syringes, which permanently increase your character's maximum health. Since steroids also refill your health, try to use them when you are low on health.

1. First, find the treasure photo located on the metal shelves near where you find the Scorpion Key in the Processing Area. Then, go to the Main House 1F, Drawing Room. Interact with one of the fireplace stones to remove the Steroids.

2. It is sold in the Yard, Trailer save room. Insert four Antique Coins on the Easy or Normal difficulty to unlock it.

3. It is located in Testing Area 1F (before the Barn), which can only be unlocked using the red and blue keycards. To get the red keycard, go to the master bedroom on the second floor after getting the Snake Key. Then, set the alarm clock to display 10:15 to open a new passage. Go inside the passage leading to the workshop to find the red keycard on the corpse. To get the blue keycard, go to Jacob's room after you get the Snake Key. Once inside, interact with the table lamp to lower the ravel. Climb up and open the dollhouse to find the blue keycard. Once you have both keycards, enter the storage room to find the Steroid syringe inside a safe. Note: Make sure to get the Steroids before triggering the Boss fight.

Very easy to miss. Find the final Steroids in the Salt Mine, in the first room of the secret lab. Look between the two bathtubs in the first room of the Secret Lab, to the right of the exit door to spot this well-hidden steroids syringe.
4. Once you reach the Salt Mine, search for the Steroid syringe between the two bathtubs in the first room of the Secret Lab, to the right of the exit door.