Cellex-C Advanced-C serum, $161/$99.51 at Amazon.com

The Ordinary Multi-peptide + hyaluronic acid serum, $19.90/$15.89 at Amazon.com

Act+Acre Daily Hydro scalp serum, $24 at Sephora

Better Screen SPF 50 serum (2-pack), $90/$45 at Kiehl’s

Sunday Riley Good Genes serum, $85 at Amazon.com

The Ordinary Retinal serum, $14.90 at Amazon.com

The Ordinary SPF 45 serum, $19 at Amazon.com

Medicube PDRN serum, $18.90 at Amazon.com

COSRX 5 PDRN Vitalizing serum, $25 at Amazon.com

Solardrops SPF 55 serum, $48 at Onekind

Jet Lag hydration serum, $44 at Summer Fridays

CC Me serum, $68 at Summer Fridays

1% Retinol treatment, $65/$48.75 at Paula's Choice

Paula's Choice Niacinamide treatment serum, $59 at Amazon.com

COSRX Niacinamide serum, $25/$19.95 at Amazon.com

Wonder Valley Wonder serum, $120 at Amazon.com

Naturium Multi-Peptide serum, $24.88 at Amazon.com

Anthony Hyaluronic acid serum, $42 at Amazon.com

The Ordinary Hyaluronic acid 2% + B5 serum, $9.90 at Amazon.com

La Roche-Posay Vitamin C12 serum, $44.99/$35.49 at Amazon.com

Vitamin C serum, $20 at Blu Atlas

Better Screen SPF 50 serum, $45/$31.50 at Kiehl’s

Hair serum, $49/$36.75 at Nutrafol

Vitamin C serum, $68/$51 at DamDam

COSRX Snail Mucin serum, $25/$18.50 at Amazon.com