They are made by adding garlic to a restore potion (which is made adding harralander and red spider's eggs to a vial of water). This gives 25 Herblore experience. Silver dust should be added to the unfinished potion to make a Guthix balance, also giving 25 experience. For maximum efficiency, it is recommended that restore potions are decanted into 4-dose potions before Guthix balance potions are created. Alternatively, if being made from scratch for the experience, making the potions at the default 3 doses would earn more experience at the cost of more materials.