Dry or dehydrated? You’ve probably used the terms interchangeably, slathered on oils, upped your water intake, and still felt like your skin was checked out by 3 pm. But according to aesthetic doctor, Dr Marwa Ali, whose clients include royalty, it-girls, and editors alike, these two skin concerns are very different, and treating one like the other can lead to even more dullness, irritation, and imbalance.
“We hear it all the time,” says Dr Marwa, from her 4th-floor suite at The Wellness Clinic at Harrods. “People come in saying they have dry skin, when really they’re just deeply dehydrated. And vice versa. The skin can feel tight, flake, look grey or tired… but the root causes are completely different.”
What’s the Difference?
“Dry skin is a skin type. It lacks oil. Dehydrated skin is a skin condition. It lacks water. One needs nourishment, the other needs hydration. Think of dry skin like cracked pavement in a heatwave, while dehydrated skin is more like a post-party crash: puffy, dull, and collapsing under your makeup.” Worse, you can have both. “It’s very common, especially if you travel, overuse active ingredients, or get hit with seasonal changes. That’s when we have to get really strategic with layering.”
The Signs
Dry skin: Usually shows up as flakiness, rough texture, tightness, and year-round discomfort, often worsened by winter weather. Makeup clings, skincare stings, and nothing seems to soak in. “It’s a skin that feels starved of nourishment,” says Dr Marwa.
Dehydrated skin: May look tired and shiny at the same time. “It’s confusing because your skin feels tight but still oily. You might notice fine lines appearing overnight, or a flat, greyish tone to your face. That’s your skin crying out for hydration.”
The Causes
Dryness is often genetic and can be aggravated by environmental. Dehydration, on the other hand, tends to stem from habits and lifestyle. “Things like long flights, stress, late nights, excessive caffeine or alcohol, and even an overzealous skincare routine can sap your skin’s moisture levels.”
Treatment That Works
Her go-to in-clinic treatment for both? The Envy Diamond Glow facial. A doctor-only procedure that uses diamond-tip exfoliation to buff away dead skin before infusing a cocktail of hydration and antioxidants deep into the dermis. “It’s not fluff. It’s functional glow,” she says. “You’ll feel the difference immediately.” Pair that with a smart home routine and you’re skin will really thank you.
For dry skin, Dr Marwa recommends rich emollients like Obagi Hydrate Luxe Moisture Rich Hydrating Cream and antioxidant oil blends such as Obagi Daily Hydro-Drops Hydrating Facial Serum. For dehydrated skin, humectant serums, especially those with polyglutamic acid, which holds four times more water than hyaluronic acid, are the secret weapon. “But remember, hydrate then seal. Otherwise, it’s like misting the air and hoping it sticks.”
And for cases where skin looks beyond tired? She swears by injectables like Profhilo or polynucleotides. “They’re like IV drips for your face. They wake the skin up from the inside out.”
What to Avoid
➼ Skipping moisturiser because your skin feels oily.
➼ Over-exfoliating or mixing too many actives.
➼ Cleansing with very hot water.
➼ Applying serums to dry skin without sealing them in.
“Your skin can be oily and dehydrated. These aren’t opposites,” she says. “And while drinking water is vital, it’s not going to save your skin on its own. You need both internal and topical hydration.”
