DERMATOLOGIST-LED GUIDE

How to Use /PHD/ Serums

A step-by-step guide to every /PHD/ serum — how to apply it, when to use it, what to pair it with, and what to avoid. Written for real results on Indian skin.

The universal rules — apply these to every /PHD/ serum

  1. Cleanse first. Always apply a serum on freshly cleansed skin — residue blocks absorption.
  2. Dry, don't damp — unless it's HA. Most actives work better on completely dry skin. The only /PHD/ serum that prefers damp application is the 2% Hyaluronic Acid Dewy Skin Serum.
  3. Pea-sized is enough. More isn't better with actives — it just increases irritation risk on Indian skin.
  4. Pat, don't rub. Press into skin with fingertips. Rubbing wastes product and stresses the barrier.
  5. Moisturiser after. Always follow a serum with a moisturiser — otherwise actives can dehydrate the skin.
  6. SPF every morning, without exception. Active ingredients make skin more photo-sensitive; skipping SPF undoes the work.

AM vs PM — when to use what

Morning serums

  • 10% Vitamin C Brightening Serum — antioxidant protection + brightness
  • 10% Niacinamide Spot Correcting Serum — oil regulation + tone
  • 2% Hyaluronic Acid Dewy Skin Serum — hydration layer under moisturiser

Finish with SPF 60 broad-spectrum. Always.

Evening serums

  • 2% Salicylic Acid Anti-Acne Serum — full-face acne treatment
  • Salicylic Acid Acne Spot Treatment Gel — targeted on active pimples
  • 2% Alpha Arbutin Depigmentation Serum — fades dark spots overnight
  • 0.3% Pure Retinol Face Serum — anti-ageing, 2–3 nights/week
  • 1% Ceramides Intensive Repair Cream — barrier repair, eczema-prone skin

Always follow with a nourishing moisturiser.

Step-by-step: each /PHD/ serum

Tap any product below to see the full how-to instructions.

2% Salicylic Acid Anti-Acne Serum 2% Salicylic Acid Anti-Acne Serum Active acne, blackheads, clogged pores

For: Active acne, blackheads, clogged pores.

  1. Cleanse with a gentle, sulphate-free face wash. Pat completely dry.
  2. Apply 3–4 drops across the acne-prone area (not just spots — salicylic acid works face-wide to prevent new breakouts).
  3. Wait 60 seconds for absorption before the next product.
  4. Follow with a lightweight moisturiser.

Frequency: Start 3 nights/week for 2 weeks, then nightly if no dryness. Use only at night.

Don't combine with: Retinol in the same evening, benzoyl peroxide, or strong AHAs. Pick one treatment acid at a time.

Shop 2% Salicylic Acid Serum →
Salicylic Acid Acne Spot Treatment Gel Salicylic Acid Acne Spot Treatment Gel Individual active pimples and inflamed spots

For: Individual active pimples, emerging whiteheads, inflamed spots.

  1. Cleanse at night and pat dry.
  2. Apply a small dot directly on each active spot (not the whole face — this is a targeted treatment).
  3. Let it dry for 30 seconds before other products.
  4. Follow the rest of your routine around the spot (avoid layering retinol on the exact same pimple).

Frequency: Once or twice daily on active spots only, until the spot flattens (usually 2–4 days).

Don't combine with: Other spot treatments on the same pimple — it over-dries and can cause post-acne dark marks.

Shop Spot Treatment Gel →
10% Niacinamide Spot Correcting Serum 10% Niacinamide Spot Correcting Serum Post-acne marks, pores, oily skin, uneven tone

For: Post-acne marks, enlarged pores, oily skin, uneven tone.

  1. Cleanse and pat dry.
  2. Apply 2–3 drops across the face, patting in with fingertips.
  3. Follow with moisturiser. In the morning, finish with SPF 60.

Frequency: Twice daily — morning and evening. One of the safest /PHD/ actives, great for daily use.

Don't combine with: Very low-pH vitamin C in the same application (pair with /PHD/'s stabilised 10% VC — they layer fine).

Shop 10% Niacinamide Serum →
10% Vitamin C Brightening Serum 10% Vitamin C Brightening Serum Dullness, sun damage, uneven tone

For: Dullness, sun damage, uneven tone, antioxidant defence.

  1. Cleanse in the morning and pat dry.
  2. Apply 3 drops, patting across the face and neck.
  3. Wait 60 seconds — Vitamin C penetrates best on dry skin.
  4. Follow with moisturiser, then SPF 60.

Frequency: Every morning for best brightening results. Optional PM use if skin tolerates it.

Don't combine with: Retinol in the same application (use Vitamin C AM, Retinol PM).

Shop 10% Vitamin C Serum →
2% Alpha Arbutin Depigmentation Serum 2% Alpha Arbutin Depigmentation Serum Dark spots, post-acne hyperpigmentation

For: Dark spots, post-acne hyperpigmentation, uneven tone on Indian skin.

  1. Cleanse in the evening and pat dry.
  2. Apply 2–3 drops across dark-spot-prone areas or whole face.
  3. Follow with moisturiser.

Frequency: Every night. Safe for long-term daily use unlike hydroquinone.

Don't combine with: Strong exfoliating acids in the same evening — alternate nights if using AHA/BHA separately.

Shop 2% Alpha Arbutin Serum →
0.3% Pure Retinol Face Serum 0.3% Pure Retinol Face Serum Fine lines, wrinkles, texture, anti-ageing

For: Fine lines, wrinkles, texture, long-term collagen support.

  1. Cleanse at night. Wait 10–15 minutes until skin is completely dry (critical — damp skin amplifies irritation).
  2. Apply a pea-sized amount across the whole face.
  3. Follow with a rich moisturiser after 60 seconds.

Frequency: Start 2 nights/week for 2 weeks. Move to 3 nights/week for 2 weeks. Then alternate nightly — only if no redness or flaking.

Don't combine with: Salicylic acid, AHAs/BHAs, benzoyl peroxide in the same evening. Never skip morning SPF after retinol nights.

Shop 0.3% Retinol Serum →
2% Hyaluronic Acid Dewy Skin Serum 2% Hyaluronic Acid Dewy Skin Serum Dehydration, dryness, every skin type

For: Dehydration, fine lines of dryness, every skin type.

  1. Cleanse with a gentle cleanser.
  2. While skin is still damp (within 60 seconds of patting), apply 3 drops.
  3. Press into skin with palms.
  4. Follow IMMEDIATELY with moisturiser to seal the hydration in — hyaluronic acid without an occlusive layer evaporates back out.

Frequency: Twice daily — morning and evening.

Don't: Apply on dry skin in low-humidity air — HA can paradoxically pull water from deeper skin layers.

Shop 2% Hyaluronic Acid Serum →
1% Ceramides Intensive Repair Cream 1% Ceramides Intensive Repair Cream Eczema-prone skin, barrier repair

For: Eczema-prone skin, compromised barrier, dryness, flaking, over-exfoliated skin.

  1. Cleanse with a sulphate-free, fragrance-free cleanser. Pat skin dry.
  2. Apply a thick layer on affected areas — face, neck, or body. On active flares, layer generously.
  3. Press in gently with clean fingertips until absorbed.
  4. No need to follow with anything extra at night — this cream is the occlusive step.

Frequency: Twice daily during a flare. Once daily (night) for maintenance. Safe for long-term daily use.

Don't combine with: Active acids, retinol, or fragranced products on an active eczema flare — pause all actives until skin calms.

Shop 1% Ceramides Repair Cream →

Layering rules — which serums work together

CombinationVerdictHow to use
Niacinamide + Vitamin C✅ SafeLayer both in AM. Niacinamide first.
Niacinamide + Alpha Arbutin✅ SafeNiacinamide AM, Alpha Arbutin PM.
Niacinamide + Retinol✅ SafeNiacinamide AM, Retinol PM. Reduces retinol irritation.
Vitamin C + Salicylic Acid⚠️ Use on alternate daysVC AM / Salicylic PM is fine. Don't stack same application.
Retinol + Salicylic Acid❌ Avoid same nightAlternate nights. Pick one treatment acid per evening.
Retinol + Alpha Arbutin⚠️ Alternate nightsUntil your skin builds tolerance. Then safe to combine.
Any serum + HA✅ Always safeHA layers with everything. Apply first, on damp skin.

The 7 biggest mistakes with serums (and how to avoid them)

  1. Using too much. A pea-sized amount is enough. More just means more irritation.
  2. Skipping moisturiser after. Actives + no moisturiser = dehydrated, reactive skin.
  3. Stacking multiple strong actives the same night. Pick one treatment acid (salicylic OR retinol) per evening.
  4. Not patch-testing. Always apply behind the ear or on the jawline for 2 days before full-face use.
  5. Giving up after a week. Most actives need 6–12 weeks to show visible results. Consistency > intensity.
  6. Skipping SPF. This undoes everything. Every morning, no exceptions.
  7. Applying on broken or irritated skin. Pause actives for 2–3 days and use only cleanser + moisturiser + SPF until the skin recovers.

Frequently asked

Can I use two /PHD/ serums together?
Yes, most combinations are safe. Generally: apply the thinnest (most watery) serum first, then the thicker one. Refer to the layering table above for specific combinations. The rule of thumb — never stack two strong treatment acids (salicylic + retinol) in the same application.
Can I use /PHD/ serums during pregnancy?
Retinol is not recommended during pregnancy or breastfeeding. Niacinamide, Hyaluronic Acid, Vitamin C, Alpha Arbutin and Salicylic Acid (below 2% concentration) are generally considered safe, but always consult your dermatologist or obstetrician first.
How long does a bottle of /PHD/ serum last?
With twice-daily use and a pea-sized amount, a 30ml bottle typically lasts 8–10 weeks. Serums should be used within 6 months of opening for full potency — especially Vitamin C, which oxidises faster.
Should I apply serum before or after moisturiser?
Always serum first, moisturiser after. Serums have smaller molecules designed to penetrate deeper; moisturisers create an occlusive layer on top that seals the serum in.
What order do I apply multiple serums in?
Thinnest to thickest consistency. Typically: Hyaluronic Acid (watery) → Vitamin C / Niacinamide (medium) → Retinol (thicker). Wait 30–60 seconds between each.
When will I see results?
Hydration: immediate. Acne: 2–3 weeks. Pigmentation / dark spots: 6–10 weeks. Fine lines and firmness: 12+ weeks. Consistency matters more than intensity — miss 3 days and you're effectively starting over.