Here's why:
* Chemical Damage: Highlighting involves using chemicals like bleach or peroxide to lighten the hair. These chemicals can weaken the hair shaft, making it brittle, dry, and prone to breakage. Doing it twice in a short period greatly increases the risk of significant damage.
* Overlapping Application: Even if you're going for a different look the second time, there's a high chance the chemicals will overlap with previously highlighted areas. This can lead to uneven results, hot spots (over-processed areas), and increased damage.
* Scalp Sensitivity: The chemicals can also irritate your scalp. Repeated application in a short timeframe can cause burning, itching, or even chemical burns.
* Hair Porosity: Processing hair makes it more porous, meaning it absorbs moisture quickly but also loses it quickly. Over-processing exacerbates this, leading to dry, frizzy hair that's difficult to manage.
Alternatives and Considerations:
* Consult a Professional: If you're unhappy with your initial highlights, talk to your stylist. They can assess your hair's condition and recommend the best course of action, which might involve a toner or gloss to adjust the color, or a deep conditioning treatment to improve the hair's health before considering further highlighting.
* Space Out Treatments: If additional highlighting is needed, waiting several weeks (or even months) is much safer for your hair's health. This allows your hair to recover and rebuild its strength.
* Protein and Moisture Treatments: If you do choose to get your hair highlighted twice close together, prioritize protein and moisture treatments to help repair and hydrate the hair.
* Lower Volume Developer: If highlights are absolutely necessary again, ask for the lowest volume developer possible. This processes more gently.
In summary, while you *can* get your hair highlighted twice in a week, it's highly advisable to avoid doing so due to the significant risk of damage. Consult with a professional stylist for personalized advice and explore alternative solutions to address any concerns with your initial highlights.