When dealing with oily hair and dandruff simultaneously, look for a shampoo that addresses both concerns effectively. Here are some characteristics to consider when selecting a shampoo for oily hair with dandruff:

1.Anti-Dandruff Ingredients: Look for shampoos containing anti-dandruff active ingredients such as pyrithione zinc, selenium sulfide, coal tar, salicylic acid, or ketoconazole. These substances help control Malassezia yeast, which is commonly associated with dandruff. Pyrithione zinc and ketoconazole also have antifungal properties, while salicylic acid aids in shedding dead skin cells.

2.Clarifying Properties: For oily hair, choose a shampoo that clarifies and removes excess sebum without stripping the scalp of its natural oils completely. Sulfate-free options might be gentler yet still effective at cleansing. Some shampoos are specially formulated to balance oil production.

3.Non-Comedogenic Formula: Make sure the shampoo doesn't clog pores or follicles, which could lead to more oil buildup and potentially worsen dandruff.

4.Gentle yet Effective Cleansing: The shampoo should clean the scalp and hair thoroughly without over-drying, as overly dry scalp can trigger more oil production and possibly dandruff.

5.pH Balanced: A pH-balanced shampoo helps maintain the scalp's natural acidity, which can help deter dandruff-causing fungus and support a healthier scalp environment.

Examples of shampoos that cater to both oily hair and dandruff include Head & Shoulders Clinical Strength Anti-Dandruff Shampoo, Neutrogena T/Gel Therapeutic Shampoo, or Nizoral A-D Anti-Dandruff Shampoo, which all contain anti-dandruff ingredients and can help with oil control. Always follow the instructions on the packaging and if the problem persists despite regular use, consult a dermatologist for professional advice.

It's essential to note that consistency in use and a complete hair care routine including conditioner (used only on the lengths of the hair, avoiding the scalp) can also contribute to better management of oily hair and dandruff.