Yes, it is recommended to add an antioxidant to your oil-in-water cream formulation containing Lanolin and Sweet Almond Oil.

Antioxidants in Cream Formulations

• Why needed: Natural oils like Sweet Almond Oil contain fatty acids that are prone to oxidation when exposed to air, light, and heat. This oxidation process leads to rancidity, causing unpleasant odors and potentially degrading other ingredients in your formulation. While Lanolin is less prone to oxidation than many vegetable oils, the presence of Sweet Almond Oil makes an antioxidant necessary.
• Oil-in-Water Emulsions: Even in an O/W emulsion where the oil phase is dispersed in water, the oil components are still susceptible to oxidation.

Natural Antioxidant Option

• Rosemary Oleoresin Extract (ROE): This is a natural extract known for its antioxidant properties, particularly effective in protecting oils from rancidity. It is a good choice for natural formulations.
• Usage Rate: Based on product information, Rosemary Oleoresin Extract (ROE) is typically used at a rate of 0.02% to 0.1% in the oil phase of the formula. It should be mixed thoroughly into the oil phase.

Adding an antioxidant like Rosemary Oleoresin Extract (ROE) will help extend the shelf life of your cream by slowing down the oxidation of the oils.