Define the goal before choosing a serum
Separate the appearance of hair density from oiliness, styling residue and scalp symptoms. A product marketed for fuller-looking hair is not automatically intended to reduce oil. Write down which result you actually want and check whether the product makes that particular claim.
If your existing routine is comfortable and your only concern is oily roots, a new cosmetic serum may add cost without addressing your goal. Keep the decision focused instead of treating a long ingredient list as evidence that one bottle solves every scalp concern.
Water-based is not the same as oil-free
The Ordinary describes its Multi-Peptide Serum for Hair Density as water-based, while its current page marks the formula as not oil-free. Those statements are not contradictory: the base format and the absence of oils are different claims. This is a useful example of why shoppers should read the full product information.
We retain it as an accessible comparison option for a multi-peptide cosmetic routine, not as a proven oil-control treatment. We have not performed a wear test on oily scalps. Compare the current ingredient list and your own preferences before deciding whether it belongs in your routine.
Check whether the application schedule fits
The Ordinary directs a few drops onto a clean, dry scalp once daily, ideally at bedtime, and describes the product as leave-in. Follow the current bottle directions rather than adding an extra dose because your roots feel oily. Do not apply to broken or irritated skin.
Before buying, picture an ordinary week. When do you wash and dry your hair? When would you apply the serum? Would it conflict with a styling routine you value? A formula with impressive marketing is still a poor purchase if its permitted use does not fit your day.
Keep cleansing decisions separate
The American Academy of Dermatology advises washing according to how dirty or oily hair becomes and notes that people with straight hair and an oily scalp may need daily shampooing. The appropriate routine varies with hair type; a blanket instruction to avoid frequent washing is not suitable for everyone.
Keep your usual tolerated routine stable while introducing a cosmetic product. Avoid adding several leave-ins at once, and record the product name and start date. If the scalp becomes irritated, stop the new product and seek advice when needed rather than interpreting discomfort as a sign of activity.
Flakes and itch are a different buying question
Dandruff care has its own product directions. AAD advises following the chosen dandruff shampoo’s instructions, which vary by formula and hair type. A peptide serum should not be presented as an interchangeable substitute for that care.
Persistent itch, soreness, heavy flaking or noticeable hair loss deserves appropriate professional advice. A shopping comparison cannot identify the cause. Avoid spending repeatedly on cosmetic serums in place of getting an ongoing problem assessed.
A practical purchase checklist
Compare the exact formula, fragrance preference, directed amount, bottle size and return policy. Distinguish the scalp serum from similarly named facial serums or supplements. Use the existing research reviews below to compare The Ordinary and The INKEY List, including their different ingredient approaches.
Start with a manageable quantity rather than a multi-bottle subscription. Record comfort and ease of use without claiming that a change in photographs proves an effect on hair growth. A product that is easy to use and honestly described is more useful than a promise of guaranteed results.
Sources & further reading
Product pages establish brand claims and label facts. They do not independently validate efficacy. Sources checked 21 September 2026.
- The Ordinary: current formula and directions
- American Academy of Dermatology: healthy hair care
- American Academy of Dermatology: dandruff care
