Botox not working: why, and what can you do?

You have had a botulinum toxin injection and you see no change, or much less than expected. Before concluding that it has failed, check how much time has passed, then consider the causes described in the official labels. This page is part of our guide to problems after an injection, which also covers adverse effects and effects that are too strong.

Is it too early to judge?

This is the first question to ask, because botulinum toxin does not act immediately. With a type A toxin, the first effects usually appear within 2 to 3 days^2,3, sometimes only within the following week¹. The peak effect is seen around day 30 for several products^2,3: a result judged after one week is therefore often not the final one.

With the short-acting botulinum toxin (serotype E), the timeline is different: the effects begin 8 hours after the injection, peak around day 7 and generally last 2 to 3 weeks⁴. If you judge the result one month after an injection of this kind, the effect has most likely already gone, which is normal. As of 9 October 2026, this toxin is approved in the European Union (since 15 July 2026) and in Canada (since 22 June 2026)^6,7.

If you do not know which product was used, ask the doctor: the short-acting toxin label actually requires the name and batch number of the product given to be recorded⁴.

When is treatment considered to have failed?

One type A toxin label defines failure as no significant improvement one month after the first session, compared with the starting point¹. Bear in mind that, even in trials, not all patients respond in the same way: thirty days after the injection, 80% of patients treated for frown lines were considered responders by the investigator¹. A partial response is therefore not necessarily abnormal.

For the short-acting toxin, data in people over 65 are limited, and the response rate at day 7 was lower in this group: 58% according to the investigator, 37% according to the patients⁴.

What are the possible causes?

When failure is confirmed, the labels ask for its causes to be analysed; they can vary^1,2:

• the choice of injected muscles: a muscle that was missed or under-treated keeps creasing the skin;
• the injection technique: depth, distribution of the injection points;
• an insufficient dose for the strength of the muscles involved¹;
• the formation of antibodies that neutralise the toxin, a rarer cause, detailed below^1,2.

According to the labels, the product itself must be kept refrigerated, between 2 and 8 °C^1,2: this is a handling requirement that falls to the medical practice.

It also helps to keep in mind what the toxin can and cannot do. It relaxes the muscles that crease the skin: it acts first on lines that form during movement. On lines already visible at rest, improvement concerns only some patients: in trials of one type A toxin, 74% of patients who had moderate to severe frown lines at rest were responders thirty days after the injection¹. One label also notes that forehead lines caused by a loss of skin elasticity, for example with age or sun damage, may not respond to botulinum toxin³. Approved aesthetic indications target lines seen "at maximum frown" or during a forced movement^1,4.

Antibodies: a rare cause

In some cases, the body can make antibodies that neutralise the toxin. The labels state that injections given too close together or at too high doses increase this risk, and that these antibodies can reduce the effectiveness of later treatments^1,2,3. A literature review identifies the same factors: short intervals, booster injections, high doses per session⁵.

In aesthetic use, this risk remains low in the available data. In trials of one type A toxin, none of the 916 patients tested developed neutralising antibodies¹. For another, no patient tested positive after repeated treatments over more than a year². For the short-acting toxin, no neutralising antibodies were found in the 2,104 patients tested, but the label states that data are still limited⁴.

The same review stresses that there is no consistent link between antibodies measured in the laboratory and the clinical response⁵: a lack of effect is therefore not enough to conclude that you are "resistant".

An effect that fades sooner than expected

Sometimes the effect did appear but wears off earlier than expected. Here again, it all depends on the product. For type A toxins approved for aesthetic use, the effect has been shown for up to about 4 months^1,2,3. For the short-acting toxin, a duration of 2 to 3 weeks matches what the label describes⁴: it is not a failure. If the effect decreases after repeated injections of a type A toxin, the labels ask doctors to consider other treatment methods^2,3.

What to do if the toxin does not work

1. Wait for the peak effect of the product used before judging: about a month for a type A toxin¹, a week for the short-acting toxin⁴.
2. Get back in touch with the doctor who performed the injection, with photos taken before the injection and at the time you judge the result, at rest and in movement.
3. Do not ask for another early injection elsewhere. Type A labels require at least 3 months between two treatments^1,3. For the short-acting toxin, repeat injections less than 6 weeks apart have not been evaluated⁴. A second session, with an adjusted dose, may be considered by the doctor after the failure has been analysed¹.

If, on the contrary, you are worried about an effect that seems too strong or in the wrong place, see our pages on the feeling of having had too much botulinum toxin and on the side effects described in the labels.

Questions to ask your doctor

• Which product was used, and when should its effect peak?
• Which muscles were treated, and which were not?
• Is the result what could be expected for my lines?
• Should another session be considered, and when?