Using expired makeup can have several long-term effects on your skin and overall health. Here are some potential risks:

1. Skin Irritation: Expired makeup can cause skin irritation, including redness, swelling, and itching. This is because as makeup ages, it can break down into harmful compounds that irritate the skin.

2. Infections: Bacteria, fungi, and other microbes can grow in expired makeup, especially in products that contain water or are stored in damp environments. These microbes can cause infections if they come into contact with any cuts or abrasions on the skin.

3. Allergic Reactions: Over time, the ingredients in makeup can degrade and potentially trigger allergic reactions. These reactions can range from mild (like a rash) to severe (like anaphylaxis).

4. Eye Problems: Using expired eye makeup, like mascara or eyeliner, can lead to serious eye problems, including conjunctivitis (pink eye), styes, and even more severe conditions like keratitis, which is an inflammation of the cornea.

5. Acne: Expired makeup can also lead to breakouts. This is because old makeup can clog pores, leading to acne.

6. Reduced Efficacy: The active ingredients in makeup can lose their effectiveness over time. This means that the product may not perform as well as it should, which can be particularly problematic for products like sunscreen.

To avoid these potential issues, it's important to regularly check the expiration dates on your makeup products and to replace them as needed. Also, remember to store your makeup in a cool, dry place and to avoid sharing makeup to prevent the spread of bacteria and other microbes.