Yes, you can use this balm both as a base under lipstick and as an overnight treatment, though the approach differs slightly for each purpose.
Under lipstick: Apply a very thin layer and let it absorb for 2–3 minutes before applying lip color. The balm provides a smoother surface and can help prevent lipstick from settling into dry lines. However, using too much or applying lipstick immediately can cause color to slide or feather. For matte or long-wearing lipsticks, blot excess balm gently with a tissue first.
As an overnight treatment: Apply a slightly thicker layer before bed. Without talking, eating, or drinking, the balm has several hours to work on reinforcing the lip barrier. The evening primrose extract's fatty acids may be particularly beneficial during this extended contact time. Many people find that overnight use helps improve lip condition upon waking, especially in dry bedroom air from heating or cooling systems.
General lip care advice suggests that overnight treatments work best when combined with daytime protection. If you use the balm heavily at night, a lighter daytime application maintains protection. Always ensure your lips are clean before applying any product, and discontinue use if you experience irritation.