"Paraben-free" and "sulfate-free" are on half the bottles in any drugstore now. Both are real ingredient groups, both are used for good reasons, and neither label tells you much about whether a product is any good.

Parabens

Parabens (methylparaben, propylparaben and so on) are preservatives. Anything with water in it, which is most shampoos, lotions and body washes, can grow bacteria and mold once you open it and start putting wet fingers in it. Preservatives stop that.

Worries about parabens mostly trace back to early-2000s studies that raised questions about hormone effects. The FDA's position is that it doesn't have information showing parabens as used in cosmetics affect human health, and European regulators allow the common ones within set limits. Plenty of brands dropped them anyway because customers asked. A paraben-free product still has a preservative in it, just a different one.

Sulfates

Sulfates, mainly sodium lauryl sulfate (SLS) and sodium laureth sulfate (SLES), are cleansers. They're cheap, they work, and they make a lot of foam. The downside is that they can strip oil, so people with dry skin, eczema, curly hair or color-treated hair often find them harsh.

Sulfate-free products use milder cleansers instead, with names like cocamidopropyl betaine, decyl glucoside or sodium cocoyl isethionate. They usually foam less, which some people read as "not working." It's working. It's just quieter.

So should you care?

• Sulfates: yes, if your skin or scalp gets dry or itchy, or your hair is curly or colored. Otherwise it mostly comes down to preference.
• Parabens: it's your call. There's no strong evidence of harm at cosmetic levels, but if avoiding them gives you peace of mind, there are good alternatives.

Reading a label quickly

Ingredients are listed from most to least, so the first five or so are most of the bottle. Look for a mild cleanser near the top if you want gentle, and humectants like glycerin or panthenol if you want something less drying.

Related: shampoo vs body wash vs shower gel and why bar soap is hard on hair.