Two abbreviations are used to describe a medicine's strength or potency. In the United States, the decimal, or x, system is more popular. In Europe, homeopaths use the centisimal, or c, system.

In both systems, potency is expressed as a number followed by an x or c, such as 3x or 6c. A potency of 1 x means a 1: 10 dilution of the original substance, or one- tenth strength (mix 1 drop of the substance with 9 drops of the dilutant, commonly water or alcohol); 2x means 1: 100, 3x is 1: 1000 and so on. In other words, the number before the x in the decimal system equals the number of zeros in the dilution, so 6x indicates a dilution of 1 part in 1,000,000. A potency of 1c means a 1: 100 dilution. The number before the c means that there are 2 times the number of zeroes in the dilution. For example, 3c means a dilution of 1 part in 1,000,000. (whereas 3x means 1 part in 1,000).

A third scale called millesimal (M) scale is also used by homeopaths. This is denoted by a number followed by the letter M, such as 1M, 2M, etc. A potency of 1M means a dilution of 1 part in 1000. The number before M means that the dilution is 3 times this number. A potency of 2M means a dilution of 1 part in 1,000,000.

Homeopathic medicines are not simply diluted. They are also shaken vigorously, or "potentized." To make a 12x dilution, one drop of the mother tincture is added to 99 drops of the alcohol or water mix and the mixture is shaken vigorously. Then one drop from this mixture is mixed with 99 drops of the dilutant and the mixture is shaken vigorously. The resultant mixture has a dilution of 1 in 10,000 (or 4x). The process is repeated a total of 6 times to get a potency of 12x. Finally, these drops are added to tiny lactose (milk sugar tablets, pillules, granules, or powder and stored in dark colored bottle.

Homeopaths believe that shaking transfers the medicine's essence to the water used to dilute it. This concept is important because solutions diluted beyond 24x (or 12c) may not contain even a single molecule of the original solution. Homeopaths believe that medicines become stronger as they become more dilute and that even when enormously diluted, the medicine's "essence" or "energy" remains.