Anyone with thinning hair or hair that has lost diameter/volume over time who wants an at-home, leave-in treatment to make existing strands look thicker and fuller. Suitable for all hair types, including color-treated hair, and used by both men and women alongside their regular Nioxin System routine.

Diamax is worth adding to a hair care routine specifically when the goal is fuller-looking hair day to day rather than a deep scalp cleanse. Because it is left on the scalp instead of rinsed out, the caffeine, niacinamide, and mint oils in the formula stay in contact with the scalp and hair longer, which is the basis for its strand-thickening claim. It is easy to fold into an existing shower routine since it goes on after washing and does not need to be washed out again, and it works for people using color treatments as well as those with natural hair.

Apply the serum directly to the scalp on wet or dry hair using several pumps, spreading it evenly. Massage into the scalp with circular motions and comb through if desired. Do not rinse out. Use daily for best results.

Pros

• Targets individual strand diameter, not just scalp cleansing, for a visibly fuller look
• Leave-in format needs no rinsing, so it fits into a normal daily routine
• Formulated with recognizable actives (caffeine, niacinamide) rather than an opaque fragrance blend
• Works on color-treated hair as well as natural hair

Cons

• Requires daily, ongoing use to maintain the thickening effect
• Addresses the appearance of strand thickness, not the underlying causes of hair loss
• Mint/peppermint content may cause a noticeable tingling or cooling sensation some users find too strong