The actress said that she always has a can of dry shampoo handy to deal with any oily outbreaks, and favours Klorane Gentle Dry Shampoo with Oatmilk.
Writing in her Goop newsletter, she said, 'This stuff's great when your hair needs a little spiffing up, especially when it's starting to get a bit greasy.
'If you want to maintain a blow dry or don't have time to do a full wash and blow out, this really does the trick. It gets right to the roots and brings back volume and makes your hair less oily.'
The 38-year-old star added that her other favourite beauty products mainly come from France.
'Many of the absolute best beauty products I've found come from regular French pharmacies,' she said. 'I always stock up on these items when I'm in France or ask friends to bring some back when they're passing through.'