For individuals with oily hair, selecting a shampoo that can effectively cleanse the scalp without over-drying is essential. Here are key features and ingredients to look for in a shampoo that's suitable for oily hair:

1. Sulfate-Free Cleansers: While traditional sulfates like Sodium Lauryl Sulfate (SLS) can provide a deep clean, they can also be harsh and strip away too much natural oil, leading the scalp to produce even more oil as compensation. Look for shampoos with gentler surfactants, like cocamidopropyl betaine or decyl glucoside, which still provide cleansing power but are less likely to over-dry.
2. Mattifying Ingredients: Shampoos with ingredients that help absorb excess oil, such as clay (e.g., bentonite or kaolin), charcoal, or rice starch, can leave hair looking less greasy and more refreshed.
3. Salicylic Acid or Zinc Pyrithione: These ingredients not only help to remove oil and dirt but also address dandruff, which can be common in those with an oily scalp. Salicylic acid acts as an exfoliant to unclog pores, while zinc pyrithione fights fungal growth that can contribute to dandruff.
4. Herbal Extracts: Natural extracts like tea tree oil, neem, lemon, or witch hazel have astringent properties that can help control oil production and soothe the scalp.
5. Lightweight Formulation: Avoid shampoos that are heavy or moisturizing, as these can weigh down fine hair and add to the oiliness. Look for products labeled as "lightweight" or "volumizing."
6. pH-Balanced: A shampoo with a balanced pH (ideally around 5.5) can help maintain the scalp's natural balance without disrupting its protective barrier.

Examples of shampoo types that cater to oily hair include "clarifying" shampoos, which are designed for deep cleaning, and those labeled as "oily hair solutions" or "anti-oil." Remember, it's important not to over-wash your hair, as this can stimulate more oil production. Washing every other day or every two days, depending on your hair's response, is often recommended for oily hair types.

Always read the labels and ingredient lists carefully, and consider doing a patch test before fully committing to a new shampoo to avoid any adverse reactions. If your oily hair is accompanied by severe dandruff or persistent scalp issues, consulting a dermatologist can provide more targeted advice and treatment options.