The science, without the marketing
How IPL actually removes hair
Understanding this is the difference between quitting in week three and having smooth underarms in week twelve. It takes two minutes to read.
1. Light becomes heat inside the follicle
Intense Pulsed Light is a broad-spectrum flash, filtered here to around 600 nanometres at 5 J/cm². That light passes harmlessly through your skin and is absorbed by melanin — the dark pigment — in the hair shaft below the surface.
Absorbed light becomes heat. The heat travels down the shaft to the follicle and damages the structures that grow new hair. The follicle does not vanish; it is weakened, and each treatment weakens it further.
This is also why IPL has limits worth stating plainly: it needs pigment to work. On white, grey, red or very light blonde hair there is nothing for the light to grab, so it will not work. On very deep skin tones, the skin itself absorbs too much of the light, which is unsafe rather than simply ineffective.
2. Growth cycles are why it takes twelve weeks
At any moment, your hair is split across three phases — actively growing (anagen), transitioning (catagen) and resting (telogen). IPL only damages follicles in the active growth phase, because that is the only time the shaft is connected to the follicle it needs to heat.
Roughly 20–30% of hairs in any area are in that phase at once. So a single session, however powerful, can only ever affect a fraction of your hair. Repeating on schedule is what catches the rest as they cycle in. This is the entire reason consistency beats intensity.
It is also why treated hair appears to keep growing for a week or two afterwards. It is not growing — it is being ejected from a follicle that has already been compromised. Resist the urge to pluck it; let it fall out.
3. Cooling is what makes it survivable
Heat in the follicle is the point. Heat on the skin surface is just pain. The INNZA handset runs a cooling plate directly behind the flash window that drops the treatment area by up to 8°C as the pulse fires, so the energy reaches the follicle while the surface stays comfortable.
Every session
Four steps, start to finish
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Shave & clean
Shave the area and wipe it dry. The light has to reach the follicle, not the hair above it.
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Pick your level
Start at 1–3 on the face, 4–6 on underarms and bikini, 6–9 on legs and arms. Climb as your skin adapts.
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Glide & flash
Auto mode fires every two seconds. Sweep slowly with a slight overlap so you do not miss patches.
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Repeat & maintain
Every 3–4 days for a month, then weekly to week 12. Top up every 4–8 weeks after that.
The twelve weeks
What to expect, and when
Put the dates in your calendar now. The people who get results are the people who keep the schedule, not the people who turn the level up.
| Period | Frequency | What you will see |
|---|---|---|
| Weeks 1–4 | Every 3–4 days | Hair sheds and regrowth begins to slow. Some patchiness is normal. |
| Weeks 5–8 | Once a week | Regrowth is visibly finer and sparser. Bald patches start appearing. |
| Weeks 9–12 | Once a week | Most areas reach their result. Coarse areas may need longer. |
| After week 12 | Every 4–8 weeks | Maintenance only, to catch follicles entering a new cycle. |
Rough session times
- Underarms 1 min
- Bikini line 2 min
- Full legs 8 min
- Arms 4 min
- Face & upper lip 1 min
- Chest & back 5 min
Read this bit
When not to use it
- On or around the eyes, eyelids or eyebrows
- Over tattoos, permanent makeup or dark moles
- On broken, irritated, infected or sunburnt skin
- Within 2 weeks of sun exposure or self-tan
- If you are pregnant or breastfeeding
- On white, grey, red or very light blonde hair
- If you take photosensitising medication
- Over the genitals, nipples or inside the ears or nose
Always run a patch test on a small area and wait 24 hours before your first full session. If you have a skin condition, a history of keloid scarring, or you are unsure whether IPL suits you, speak to a doctor first. This device is a cosmetic appliance, not a medical treatment.
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