Does slugging (smearing your skin with petroleum jelly) actually work?
Petroleum jelly genuinely works as a sealing layer that reduces moisture loss, but for structurally dry skin or barrier repair you will get more benefit by also using a ceramide moisturiser.
Petroleum jelly does indeed seal the skin effectively. It reduces moisture loss through the skin measurably better than plant-based oils or mineral oil: laboratory studies measure 40 to 60% swelling of the outermost skin layer with petroleum jelly, compared with 10 to 20% for those alternatives. That is the mechanism behind slugging: your skin loses less moisture overnight.
When the skin barrier is damaged, for example after irritation or with eczema, petroleum jelly can temporarily cover that barrier and support its recovery. This has been demonstrated in laboratory models, and petroleum jelly is recognised in dermatology as one of the treatment options for eczema. However, large clinical trials in healthy individuals are still lacking.
For dry skin over the longer term, more modern formulas containing ceramides or other lipids that mimic the skin's own structure appear to work better than petroleum jelly alone. Petroleum jelly creates a seal, but it does not add the building blocks the skin itself needs in order to become stronger. If you suffer from structurally dry skin, you will get more benefit from using a ceramide moisturiser, with petroleum jelly applied on top of it if desired.
There is one important safety signal worth mentioning. In infants who received frequent oil baths, the skin looked less dry, but actual transepidermal water loss was temporarily higher. This shows that skin that looks good does not always mean a stronger skin barrier. This research concerned mineral oil in infants, not adults practising slugging, but the principle applies more broadly: the appearance and the function of the skin can diverge.
Claims based on laboratory studies, in-vivo measurements and a randomised trial (ceramides vs. occlusives). No large RCTs specifically on the slugging habit in adults. PMIDs: 18164596, 36863326, 20572888, 14572299, 22882126, 38446755, 27931536, 29319217.
Does snail mucin actually work for your skin?
Snail mucin shows promising effects in laboratory and cell studies, but clinical evidence in humans is still largely absent. In addition, there are no quality standards and allergy research has barely been done, so use it with care if you have sensitive skin.
Does taking collagen supplements actually work against wrinkles?
Hydrolysed collagen reduces wrinkles and can improve hydration and elasticity. Take 2.5 to 5 grams per day for at least 8 to 12 weeks, and choose a product with 'collagen peptides' or 'hydrolysed collagen' on the label. Marketing promises about spectacular skin rejuvenation are exaggerated.
Does resveratrol in skin cream actually do anything?
Resveratrol in skin cream demonstrably reaches the skin and has antioxidant activity, but whether it produces any visible effect as the sole active ingredient has not yet been proven. Combination products show promising results, but anyone buying a cream with resveratrol should be aware that the evidence for resveratrol itself remains thin.
Does skin cycling actually work better for your skin?
Skin cycling as a protocol has not been scientifically tested, so no proven benefit can be attributed to it. Some of the ingredients it features, such as ceramide moisturisers and nicotinamide, do have solid evidence behind them individually.
Does hyaluronic acid applied to your skin actually help against dryness and wrinkles?
Hyaluronic acid on your skin genuinely helps against dryness. Injections work most powerfully against wrinkles. A pill or powder adds little if you are already taking collagen.
Do cold showers really make your skin tighter?
Cold showers do not make your skin tighter; frequent showering can actually damage the skin barrier and cause dry skin, regardless of the water temperature.