Understand your skin before you buy anything for it.

Only if you were dehydrated to begin with. Water you drink is regulated by your kidneys and does not travel preferentially to your face, so going from adequate to excessive changes nothing. Going from dehydrated to adequate does show, mostly around the eyes and in overall dullness. The full answer, with a calculator.

They mostly remove sebaceous filaments, which are normal anatomy and refill within about thirty days. Meanwhile they strip the barrier, and repeated use can leave pores looking larger than when you started. The satisfying result on the strip is not the result on your face. More on this.

No — and this is the one on this list where the stakes are highest. Topical steroids suppress inflammation without treating its cause, and on facial skin they can produce thinning, permanent broken capillaries, and a rash that worsens each time you stop. They also mask infections while those spread. Why they are prescription-only.

Skin turnover takes roughly a month, so nothing meaningful happens in a week. Give most actives eight to twelve weeks before judging them, and change one thing at a time — otherwise you will not know which thing worked.

Two associations hold up reasonably well: high-glycaemic diets, which raise insulin and in turn sebum production, and dairy — oddly strongest for skim milk. Both effects are modest and neither applies to everyone. Chocolate and greasy food as such have much weaker evidence than their reputation suggests. The evidence in full.

Lying flat removes the gravitational drainage your face gets all day, so fluid pools where the skin is loosest. Salt eaten late, alcohol, and poor sleep all make it worse. Sleeping with your head slightly raised is the single most effective fix. More on fluid balance.

Almost certainly not. Two to three times a week suits most people. Daily exfoliation strips the barrier faster than it rebuilds, and the resulting tightness and breakouts are often misread as needing more exfoliation, which deepens the problem. Choosing the right acid.

Sometimes, but rarely in proportion to the price. Formulation, texture and finish genuinely improve at higher price points; the active ingredients often do not. A cheap cleanser and an expensive one both clean your face. Where money is worth spending is sunscreen you will actually wear every day.

It depends heavily on where the feeling comes from. People changing one specific feature they have considered for a long time tend to be satisfied. People hoping a procedure will change how they feel in general usually are not, because surgery changes the feature rather than the relationship. What to consider first.