Heavy conditioners flatten thin hair, so the second row keeps things light. Oribe, co-founded by the stylist Oribe Canales in 2008, makes a densifying conditioner from its Serene Scalp line. Vegamour, which Daniel Hodgdon founded around red clover and mung bean, makes a revitalizing conditioner. Fable & Mane grew out of a grandmother's head massages and fables, and its conditioner matches the shampoo. Act+Acre uses a patented cold-processed method that mixes plant ingredients with ice-cold water under pressure instead of heat. Condition only from the mid-lengths down, so the roots stay lifted. Rinse well, because leftover conditioner weighs hair down as much as a heavy formula does.

Caudalie's density serum uses soothing peptides, from a brand that started when a Bordeaux pharmacy professor told the founders grape seeds were being thrown away. Nécessaire's scalp serum carries 5 percent Capixyl, and Moroccanoil's tonic is a weightless spray for thicker-looking hair. Virtue's Flourish styling treatment uses Alpha Keratin 60ku, a protein that came out of regenerative medicine research into wounds and burns. What I would skip is stacking several scalp serums at once. You will not know which one helps, and more product can irritate. Pick one and give it three months. Most scalp products need that long before you can fairly judge them.

Wash often enough that the scalp stays clean, since oil flattens fine hair fast. Blow-dry upside down for lift. Use a light styler instead of heavy creams. Take a photo each month so you can judge any change honestly, in the same light and from the same angle. A good cut with some layers can also add more visible fullness than any product. If you want to keep browsing, I also put together What a Hair Growth Shampoo Can and Cannot Do for Thinning Hair and Better Not Younger, Hair Care Built for Thinning Hair.