Starting your home phototherapy safely

Updated on 
Nov 24, 2025
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Key takeaways

We’re excited to support you as you begin your at-home phototherapy journey. Used correctly, light therapy is safe, effective, and one of our most powerful tools. Please read everything carefully before your first treatment.

Universal Rule:  No matter your Fitzpatrick skin type, the first session must always be 15 seconds. This overrides all charts and online guidance.

Step 1: When Your Device Arrives

As soon as your phototherapy machine arrives:

Do NOT start treatments until we confirm your settings.

Helpful “How-To” setup videos:

Step 2: Your First Session

  • Your very first treatment must be 15 seconds total: this rule applies to all skin types (I–VI).
  • We will guide increases based on your skin type (Fitzpatrick score) and response.
  • Never skip ahead or increase faster than advised.
  • If you notice tenderness, burning, blistering, or intense redness, stop immediately and message us.

Step 3: Safety & Monitoring

  • Wear your protective goggles every session.
  • Cover sensitive areas (face, genitals) unless told otherwise.
  • Avoid applying lotions, moisturizers, or steroid creams right before sessions.They can increase UV absorption.
  • Log each treatment (time, redness level, comfort). This helps us adjust your plan safely.

Step 4: When to Contact Zest

Please message us right away if:

  • Redness lasts more than 24 hours
  • You develop stinging, blistering, or swelling
  • You need help adjusting your dose or schedule

A. Safe Dose Progression (After Session 1)

Fitzpatrick Type
Starting Dose
Typical Max Range
Increase per Session
Notes

All Skin Types (I–VI)

15 seconds only

Manufacturer-required

I–II

Increase after 15 sec

~2–3 min

+10–15%

Higher burn risk

III–IV

Increase after 15 sec

~3–4 min

+15%

Moderate tolerance

V–VI

Increase after 15 sec

~5+ min

+15–20%

Higher max ceilings

Important: Even darker skin types (V–VI) must still start at 15 seconds.

B. What to Do If Redness or Tenderness Occurs: These are Phothera-required safety rules.

1. Mild pinkness or slight tenderness (<24 hours)

Repeat the same dose next session (do NOT increase).
Example:

  • Last dose: 60 sec
  • Repeat: 60 sec

2. Painful redness or tenderness lasting 24–48 hours:

 Decrease dose by 15% before resuming increases.
Example:

  • 15% of 60 sec ≈ 9 sec
  • New dose: 50 sec

3. Painful redness lasting more than 48 hours:

   Decrease dose by 30% and wait until fully recovered before continuing.
Example:

  • 30% of 60 sec = 18 sec
  • New dose: 40 sec

4. Still red or irritated at your next scheduled treatment:

 Reduce the dose by an additional 25–50%, depending on severity.
Example:

  • 25% reduction (mild): 60 sec → 45 sec
  • 50% reduction (clear irritation): 60 sec → 30 sec

C. Missed Treatment Rules

Time Since Last Treatment
What To Do

4–7 days

Repeat last dose

8–14 days

Decrease by 25%

15–21 days

Decrease by 50%

22+ days

Restart at 15 seconds

Sample Dose Progression (Fitzpatrick III; +15% per session)

  • Session 1: 15 sec
  • Session 2: 15 × 1.15 = 17 sec
  • Session 3: 17 × 1.15 ≈ 20 sec
  • Session 4: 20 × 1.15 ≈ 23 sec
  • Session 5: 23 × 1.15 ≈ 26 sec

Continue this pattern until you reach your typical max (180–240 sec).

If you have any questions, please reach out to your Zest Care Team via your Zest portal. 

The Skin Deep Summary
Sources