Can I put this on face and scalp? I sweat a lot on scalp and face hard to wear makeup.

You can spray antiperspirant like this basically anywhere. It's not scented or anything, it's just antiperspirant, alcohol and dimethicone. You can use it on your groin I'd you want. I spray it on my scalp cause I don't like how it gets sweaty above my forehead. The only thing is it's just harder to spray there. Your hair is kinda in the way. I pull my hair back before I spray and that helps. It also leaves a residue in your hair.

Is this safe? Can I get a complete list of ingredients?

I don't know about a complete list of ingredients, but I have been using this product for over 10 years. It's a little harsh if you have sensitive skin for the first week or so. Just spray on hand and rubbing instead of directly on to the location. I used to order it from the Neitherlands. Now I just get it here. Hope this helps.

Does anyone know why it can only be used at night?

I have been using odaban fir over 20 years due to hyoerbydrosis. I usef to buy it directly from England (or maybe Australia??). In the beginning I tried it during the day. It teally does not work as well. It should be applied to clean, DRY skin (meaning while sleeping when you are not sweating). Then, it is washed off in the morning before applying deodorant. This is a miracle product, but you must stick with it in the beginning. Now I only use it once, maybe twice per month.