We washed our son's hair every time we gave him a bath and we started giving him a bath at least once every other day when he came home from the hospital.
When choosing a baby shampoo it's pretty important to choose something that's not toxic to your baby. I find
Environmental Working Group's Skin Deep Cosmetic Safety Database to be pretty helpful for finding out what exactly is in the products we use every day and how good/bad they are for us.
Here is a search for the popular Johnson and Johnson's No More Tears shampoo which reveals that because of the chemicals used in the shampoo (you can find out the specific components of the shampoo and what they do to your body) are moderately hazardous (on a scale of low to high hazard) to the human body. Also remember that a baby's skin is very sensitive and that we can actually absorb chemicals through our skin.
Johnson and Johnson actually doesn't have the safest products out there--some of their products were recently taken off store shelves in Taiwan because the level of toxicity was too high.
Here are my recommendations for shampoos/soaps to use with your baby.
1. J.R. Liggett's Old-Fashioned Bar Shampoo
I am not sure if you can buy this in Hong Kong but you probably can buy it online and it comes in a small cube so having it shipped shouldn't cost much--you could buy an entire shoebox of it and each cube is the equivalent of a bottle of liquid soap. Lathers up beautifully. Smells nice. Comes wrapped in simple paper so very little waste to throw away.
2. Sakura Honey Soap from Japan. I've bought this soap in several different local dispensaries. The bar I'm holding in my hand right now cost $32 HKD and will last for about 2-3 months as long as its put on a dish that doesn't sit in the shower where it can get wet and "melt." Although this soap is meant for use on the body, I also use it on my son's hair--I lather up a bit, rub it through his hair and rinse. It's a light, simple soap that avoids a lot of the toxicity of most shampoos.
3. Burt's Bees. Burt's Bees is pH balanced,
sodium lauryl/laureth sulfate free,
paraben free and
phthalate free.
You can get Burt's Bees in several places including some Mannings stores. I think that I last saw a supply counter at Mannings in the IFC building. The products are a bit expensive but I have bought one bottle of More Moisture Raspberry & Brazil Nut Conditioner and it has lasted over 6 months--I only use it on my son so the product lasts for a long time.
Hope some of this information is helpful.