The Ordinary glycolic toning and the ordinary Niacinamide

Niacinamide (Vitamin B3) is indicated to reduce the appearance of skin blemishes and congestion. A high 10% concentration of this vitamin is supported in the formula by zinc salt of pyrrolidone carboxylic acid to balance visible aspects of sebum activity.

Contraindications: If topical Vitamin C (L-Ascorbic Acid and/or Ethylated L-Ascorbic Acid) is used as part of skincare, it should be applied at alternate times with this formula (ideally Vitamin C in the PM and this formula in the AM). Otherwise, Niacinamide can affect integrity of the Vitamin C

Glycolic Acid is an alpha hydroxy acid that exfoliates the skin. 
This 7% toning solution offers mild exfoliation for improved skin radiance and visible clahis pH of this formula is approximately 3.6. Glycolic Acid has a pKa of 3.6 and pKa is the most important aspect to consider in formulating with acids. pKa implies acid availability. When pKa is close to pH, there is an ideal balance between salt and acidity, maximizing effectiveness of the acid and reducing irritation. Higher pH numbers in such a case would increase salt which counter-intuitively would make the formula even more irritating than if the formula was more acidic.