Sagging is two problems, and most treatments fix only one.

Laxity is, in large part, what sun and smoke do to elastin. In the Nambour trial, daily sunscreen users showed no detectable increase in skin aging over 4.5 years — 24% less than discretionary users (Hughes 2013). Skin biopsies from 69 people found smokers' elastic fibres altered in proportion to cumulative tobacco dose, acting additively with solar elastosis (BJD, 2007); the reviews of smoking and sun on aging skin describe the same enzyme-driven breakdown (JID review), and among identical twins the smoker sags first (twin study). Strong here because, unlike a fold or a jowl, laxity is the skin's own problem and these are the two habits with evidence on the skin's own mechanism.

Hydrolysed collagen peptides are absorbed as small fragments that appear to signal fibroblasts to make more matrix, and the trials measure exactly the property this page is about. A 2023 review of 26 studies, mostly in women, found 1–12 g a day for 4–12 weeks improved skin elasticity and hydration (2023 review); a separate review of 19 trials in 1,125 people aged 20–70 reached the same conclusion (19-trial review); and a randomised controlled study of 79 menopausal women found 5 g a day for six months raised skin elasticity to 108–112% of baseline with hydration up 23%, against negligible change on placebo (menopausal RCT). The caveats are the ones the collagen guide spells out: short trials, small samples, cutometer endpoints, and manufacturers paying for most of them. A 2025 meta-analysis that found no effect in the few independent trials goes too far: two of them gave only 1–2 g a day, and the clearest negative one measured forearm skin in women aged 60 to 93 (2025 meta-analysis; our reading of it).

Take about 10 g a day with vitamin C and other skin nutrients, and give the sagging skin a local signal to build collagen, such as the retinoid above or a collagen-stimulating treatment; collagen alone at a low dose may not be enough. Strong for elasticity, and still not a lift.

Tretinoin thickens the epidermis and drives fibroblasts to lay down new upper-dermal collagen, which is the tissue laxity lacks; the meta-analysis of eight randomised trials in 1,361 patients found significant improvement in fine and coarse wrinkles over vehicle (meta-analysis). No trial has used laxity or a cutometer as its endpoint, and the effect is dermal quality over a year rather than a change in where the skin sits — moderate for this problem, and the base under everything else. The wrinkles guide covers the ladder from retinol to tretinoin.

Two actives have controlled trials with elasticity or wrinkles as endpoints: niacinamide 5% reduced fine lines and improved elasticity in a 12-week double-blind split-face trial (Bissett 2005), and a 5% vitamin C cream reduced deep furrows over six months in a double-blind trial (Humbert 2003). Peptides, growth factors and "firming" complexes are marketed on the same mechanism with less evidence. All of it is dermal quality on the surface layer; none reaches the fat, the bone or the ligaments. The wrinkles guide grades the shelf.

Nobody should keep weight for a face, and the trade should be known. Imaging shows deep and superficial facial fat both lost with weight loss and the midface losing most (ASPS); after massive loss, faces were judged about five years older (systematic review); and the GLP-1 literature reports laxity, volume loss and hair shedding in proportion to weight lost, with possible direct effects on the cells that rebuild skin (Ozempic-face review; mechanisms review). Slow loss lets younger skin retract; older skin will not, and the plan is volume replaced and, for a large envelope, surgery. A small series reports diluted calcium hydroxylapatite preserving facial volume during GLP-1 weight loss (series). Emerging because nobody has randomised the pace of a diet.

Skin repairs at night, and the deficit shows first in recoil: when 32 Korean women in their forties slept eight hours a night for six nights and then four hours for six, hydration fell after one night and elasticity was the property most affected, with wrinkles and gloss worsening from day one (sleep-restriction study); in 24 women, two nights of three-hour sleep reduced the skin's extensibility (24-woman study). Sugar stiffens what is left: advanced glycation end-products, measured by skin autofluorescence, accumulate with age and body-mass index and track the loss of elasticity (glycation study), and cross-linked collagen neither stretches nor repairs (review). Emerging because the studies are small and observational; free because the fixes are.

Microcurrent devices pass a small current through the facial muscles to make them contract, on the theory that a toned muscle supports the skin above it. The one randomised trial is better than the category's reputation: 108 women aged 32–58 used a neuromuscular electrical-stimulation device for 20 minutes a day, five days a week, for 12 weeks, and more than 80% reported improved firming, tone and lift against under 5% of controls, with zygomaticus muscle thickness up 18.6% on imaging (Kavanagh 2012). It was partially blinded and self-reported, and the leading consumer brand's own studies are single-arm (manufacturer studies). Plausible for muscle tone, nothing for the dermis, and it stops when you stop.

Red and near-infrared light stimulate fibroblasts, and the reference trial randomised 113 of 136 people to light, against 23 untreated controls, with measurable gains in complexion, roughness and collagen density on ultrasound (Wunsch & Matuschka 2014); a home mask has a sham-controlled trial for crow's feet (sham-controlled trial). Nobody has measured laxity, consumer devices deliver a fraction of the clinic dose, and the mechanism is dermal quality rather than tightening. The red-light guide covers doses and devices.

Home radiofrequency wands deliver a fraction of clinic energy and rest on manufacturer-run studies (manufacturer study); gua sha and rollers shortened facial contour distances by 2–3 mm, and the roller raised skin-elasticity readings, after eight weeks of daily use in a trial with no untreated group (2025 trial); the 20-week facial-exercise pilot in 16 women found blinded raters judging cheeks fuller, with no control group and no laxity measure (Alam 2018). None reaches the dermis at a dose that remodels it or the structure beneath. Pleasant, harmless, not a line on the plan.

Estrogen maintains dermal collagen, hyaluronic acid and elastic fibres, and replacing it after menopause is the one systemic intervention on this page with pooled evidence: a 2023 systematic review and meta-analysis of 15 studies in 1,589 women found menopausal hormone therapy significantly increased skin elasticity (standardised mean difference 0.28), skin thickness (1.27) and collagen content (2.01), with reduced wrinkle severity (meta-analysis). The trials underneath are small: 40 postmenopausal women randomised double-blind to estradiol–dydrogesterone or placebo for seven cycles showed elasticity at the jaw and skin thickness rising in the hormone group, though the absolute effects did not differ significantly from placebo (2007 RCT); 41 women on cyclical estradiol valerate with cyproterone acetate for six months gained 6.5% collagen in upper-arm biopsies, and nothing else measured changed (2000 RCT); the narrative reviews add that results are inconsistent across older trials (2025 review).

Nobody should start hormone therapy for skin, and the guidelines do not recommend it for that; the Menopause Society's position statement sets out for whom the benefits outweigh the risks — symptoms, bone, timing within ten years of menopause, transdermal routes for clot risk (position statement). For a woman who is a candidate on those grounds, firmer skin is a documented side benefit. The 50s guide covers the decision.

Where the frame has shrunk, the envelope hangs, and the fix is the frame. Restoring midface volume with a firm hyaluronic gel had a control group in its pivotal programme — 235 patients, 85.6% improved at least one grade at six months — and 79% still rated their cheeks improved at two years (pivotal RCT; two-year outcomes); autologous fat matched hyaluronic acid over nine months in a 62-patient randomised comparison for the folds (Hu 2017). It is the right tool for the deflated type and the wrong one for thin, crepey skin, which shows every gel beneath it; and hyaluronic gel persists for years on MRI, so the overfilled face is the risk of treating laxity with volume (MRI review). The filler guide grades the products.

Poly-L-lactic acid provokes fibroblasts to build collagen over months, so it adds dermal substance and deep support at once — the combination the deflated, thinned face needs. The evidence sits in the nasolabial fold: a randomised evaluator-blinded trial of 233 patients found it more effective than collagen from month 3 to 13 with correction persisting to 25 months (Narins 2010), and a 252-person multicentre double-blind randomised trial of a microsphere formulation found it ahead of hyaluronic acid at 48 weeks (2026 RCT). No trial has used laxity as its endpoint, the result arrives over months and depends on the injector, and nothing dissolves it. The regenerative guide grades the biostimulators.

Five boluses of a high-and-low-molecular-weight hyaluronic complex per side of the face spread through the dermis to hydrate it and, the claim goes, remodel it. The systematic review of nine studies in 278 participants found statistically significant improvement or a trend in viscoelasticity and elasticity parameters, plus hydration, density and laxity ratings, with mild adverse events resolving within 72 hours — and most of the studies uncontrolled (systematic review). The controlled evidence is smaller: a randomised triple-blind split-face trial of 12 women saw wrinkles and pores improve, but dermal thickness rose on the saline side too and over half of the women were dissatisfied (triple-blind RCT), and a 20-person randomised trial found adding it to toxin for the upper face gave no clinical or ultrasound advantage at three months (2026 RCT). Hydration for the thin-skin type; not a lift, and priced as one. The filler guide grades the boosters.

Calcium hydroxylapatite diluted one-to-one or more and fanned through the dermis and superficial fat provokes collagen and elastin around each microsphere; biopsy work shows type I and III collagen and elastin rising. The measurements come from small series: in ten women, upper-arm skin elasticity rose from 72 to 82 cutometer units at three months, and in another ten, abdominal dermal thickness rose 27% on ultrasound, with 90% rated much improved (case series); a retrospective lower-face series of 22 patients measured jowl volume down 41% and fold depth down 27–28% at day 150 (lower-face series); protocol papers cover face, neck, décolletage and hands (protocols). No randomised trial for laxity — the one randomised trial measured chest wrinkles (Radiesse décolleté trial) — and no enzyme to remove it. Emerging, and the most objectively measured of the biostimulators. The regenerative guide covers the class.

Purified DNA fragments from fish injected into the dermis are claimed to signal repair and improve turgor. The systematic review found nine studies of low to moderate quality in 219 patients, reporting reduced wrinkles, better texture and enhanced elasticity with statistically significant results in several, mild transient side effects, and a call for higher-quality research (systematic review); a randomised double-blind split-face trial of 27 people around the eyes favoured polynucleotides over hyaluronic acid for elasticity, hydration, roughness and pore volume, with dermal density no different (split-face trial). Emerging on that basis; skin quality in the thin-skin type, nothing for descent. The regenerative guide grades the class.

Platelet-rich plasma has three randomised split-face trials showing modest gains in texture and fine lines, largely when combined with microneedling, and none measuring lift or laxity (split-face trials); a 2025 review found skin thickness improved in 80% of studies but wrinkles in only 40% (2025 review). Exosome products are unapproved biologics with regulator alerts and no controlled trial for laxity (FDA notification). Defensible as a skin-quality add-on after a device; a "PRP lift" is a name. The regenerative guide covers both.

Barbed absorbable threads catch tissue and hitch it upward for a while; they do not change the skin's recoil, and the lift does not last. In a randomised trial, the elevation had returned to baseline by 60 days regardless of how many threads were placed (randomised trial); a systematic review puts the complication rate near 27% — dimpling 11%, bruising 8%, extrusion and migration (systematic review; complications meta-analysis). Limited for laxity because they treat neither of its causes. The jowls guide grades them for the lower face.