In short. The flat period is the hardest part of the course. Why it exists, why it is exactly where people wrongly conclude the treatment failed, and how to get through it.
Key points
- Photograph the area in the same light, at the same distance and angle, at fixed intervals, and put the mirror away between them.
- Memory is unreliable in both directions over weeks, and the review at three months exists to replace it.
- If the plan did not describe this period in advance, ask for it to be described now.
Every treatment has a difficult part, and for this one it is not the injections. It is the stretch after them, when the collagen response is under way, nothing is visible, and the patient has no evidence that anything was done at all. Knowing why that period exists is what makes it survivable. It is also the single most useful thing an assessment can explain.
Why nothing appears
The material is placed as particles that the tissue responds to by laying down collagen around them. That response is biological and it takes weeks. Unlike a substance carried in a gel, there is no volume on the day to be seen and then watched as it disappears, so the appointment ends with no visible change at all and the following week may look identical to the one before it. The work is happening at a level the eye cannot see. A patient who expects a gradual appearance will read the flat weeks correctly; a patient who expects something will read them as failure.
Where the course is abandoned
People do not stop a course in the third month, when the change is beginning to show. They stop in the fifth week, when nothing has changed and continuing feels like paying for nothing. That is the cost of the delay: it acts on the patient precisely when there is the least information available.
What to do with the flat weeks
Photograph the area in the same light, at the same distance and angle, at fixed intervals, and put the mirror away between them. Memory is unreliable in both directions over weeks, and the review at three months exists to replace it. If the plan did not describe this period in advance, ask for it to be described now.
Why adding sessions early makes it worse
The instinct when nothing is visible is to add more material, and it is the most damaging thing that can be done in this window. The tissue has not finished responding to what is already there, so a second session on top of an unfinished response produces an uneven result rather than a faster one. Because nothing dissolves this substance, an area that is over-treated has to be waited out or treated, and that is a considerably longer problem than the flat weeks themselves.
Findings that are not part of the flat period
- A firm lump that is growing, is painful, or is visible rather than merely palpable under the skin.
- Redness, warmth, increasing swelling or pain over a treated area, or any fever.
- Skin over the area that changes colour, blisters, or breaks down.
The change usually starts to appear between two and three months, and it continues between sessions rather than after each one. The effect also keeps building after the final injection, which is why the result is judged between six and twelve months. A patient who has been told all of that in advance has been given the only thing that makes the flat period tolerable: a reason for it.
Frequently asked questions
How long does the flat period last?
Usually from about the second week to the sixth, and sometimes a little longer. During that stretch the treated area may look exactly as it did before. The first visible change normally appears somewhere between two and three months, gradually and unevenly.
Does an unchanged area mean the treatment has not worked?
No. It means the collagen response is not yet visible, which is a different thing. Nothing in the first six weeks tells you whether the course is working, which is why judgement belongs months later and against standardised photographs rather than the mirror.
Should I book an extra session if nothing is showing?
No, and that is the most important thing to understand about this period. Adding material before the tissue has finished responding is how an area becomes over-treated, and no dissolving agent exists to correct it. The answer to a flat month is patience, not a session.
Risks & Limitations
- Irreversibility: there is no agent that reverses this substance. An uneven or unwanted result is managed over time, with injected treatment, or occasionally by removal, and never switched off.
- Nodules and granulomas — firm lumps or an inflammatory reaction that can appear weeks or months after treatment, most often in the window when the result is being judged.
- Unevenness or over-correction, which is harder to correct than under-treatment in an area that cannot be dissolved.
- Nothing is visible on the day and the treated area may look unchanged for several weeks. This is expected rather than a sign the treatment has failed.
- Infection or inflammation at an injection site, which needs prompt assessment rather than waiting.
- Tenderness, swelling, occasional bruising and occasional headache after treatment.
- The result develops over months, cannot be judged before six months, is not permanent, and declines gradually after its fullest point; the face continues to age.
When to Seek Care
- A firm, growing or painful lump at or near an injection site, appearing weeks or months after treatment — this needs assessment even when it is not painful.
- Redness, warmth, swelling or pus at an injection site, or fever.
- Skin breakdown, blistering, or a dusky or mottled patch over a treated area — seek care immediately.
- Increasing pain, or pain out of proportion to the injection.
- Difficulty breathing, facial swelling or a widespread rash — possible severe reaction; seek emergency care immediately.
References & Further Reading
- American Academy of Dermatology (AAD) — injectable and skin safety information
- American Society of Plastic Surgeons (ASPS) — injectable treatment guidance
- U.S. Food and Drug Administration (FDA) — approved injectable products and safety communications
- National Medical Products Administration (NMPA, China) — approved product status
- Chongqing West District Hospital — Plastic Surgery & Aesthetics Medical Center
This page is patient education, not medical advice, and it does not cite individual studies. Discuss your own case with a qualified clinician. To arrange an assessment at Chongqing West District Hospital, see Contact & Consultation.