Nano brows, also known as nano needling, is a semi-permanent eyebrow tattooing technique that uses a needle to create the illusion of fuller, more defined eyebrows. Like any cosmetic procedure, it is not without its potential side effects and risks.

1. Infection: As with any procedure that breaks the skin, there's always a risk of infection. This can be minimized by following proper aftercare instructions and ensuring the procedure is carried out in a clean, sterile environment.

2. Allergic Reaction: Some people might be allergic to the pigments used in the procedure. While this is rare, it's important to discuss any known allergies with your technician before the procedure.

3. Scarring: If the needle penetrates too deeply or if the skin is not properly cared for after the procedure, scarring can occur.

4. Unsatisfactory Results: There's always a risk that you won't be happy with the results. It's important to have a thorough consultation with your technician before the procedure to discuss your desired outcome.

5. Color Changes: Over time, the pigments used in nano brows can fade or change color. This is a normal part of the process, but it can result in the need for touch-ups.

6. Granulomas: These are nodules that can form around material that the body perceives as foreign, such as the pigments used in nano brows.

7. MRI Complications: In some cases, the pigments used in nano brows can interfere with MRI imaging.

8. Keloid Formation: People who are prone to developing keloids, which are raised scars, may experience keloid formation after the procedure.

9. Hepatitis and HIV: If the needles used are not properly sterilized, there's a risk of transmitting bloodborne diseases like Hepatitis B, Hepatitis C, and HIV.

To minimize these risks, it's important to choose a reputable, licensed professional to perform the procedure and to follow all aftercare instructions carefully.