
Originally Posted by
elastica
There's a brand of shampoo with caffeine called "Alpecin." It's said to contain 2% caffeine. So if you wanted to make a 2% solution you'd need to add about 5 grams to 250 mL of liquid, assuming the shampoo mix has about the same weight as water.
I've seen recipes online that suggest adding 2 teaspoons per 8 fluid ounces, some say 4 teaspoons per 8 fluid ounces. I put about 3 in 500 mL, 16.9 fluid ounces, along with some essential oils. Daily gentle scalp massage can be helpful to stimulate hair growth too.