Botulinum toxin resistance: does it really happen?

Key points

1. (1).

   Resistance means the body makes antibodies that block the drug (neutralizing antibodies); it is not the same as “feeling that the effect got shorter.”

2. (2).

   A 2023 meta-analysis of 33 trials found antibodies in 27 of 5,876 people (about 0.5%), and only 5 of them were judged to have lost the effect. 8 of its 12 authors were manufacturer employees, and the data mix 10 indications beyond cosmetic use.

3. (3).

   An independent 2022 meta-analysis (43 studies, 8,833 patients treated for medical reasons) put the rate at 1.8%, rising to 7.4% in dystonia, with a trend toward more antibodies the longer people were treated.

4. (4).

   Data on cosmetic use alone are limited, so the exact rate for cosmetic injections has not yet been pinned down.

5. (5).

   Besides antibodies, storage and handling, injection technique, intervals shorter than 3 months, large single or cumulative doses, and top-ups within 3 weeks have been suggested as factors, but these come from a narrative review and are a list of suspects, not proven causes.

When to see a doctor

See a doctor if there is almost no change in movement 2 weeks after injection on 2 or more occasions, if there was no response at all from the first time, or if swallowing feels difficult or muscles far from the injection site feel weak.

FAQ

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