Background Clostridium botulinum toxin type A (Botox), a neurotoxin complex, inhibits the release of acetylcholine at the presynaptic membrane on cholinergic neurons.

Because of reports of variability in the literature regarding treatment duration and adverse effects of botulinum toxin, we reviewed the results of the Neurology Department of our hospital.

Purpose To determine the efficacy and safety of Botox in the patients treated in the Neurology Department of our hospital, and to compare the results with those published in the product information (PI) provided by the pharmaceutical company.

Materials and methods A retrospective observational analysis of all neurological patients treated with Botox for 4 years.

We reviewed the medical records of the hospital and Primary Care.

We evaluated doses, duration of effect and adverse reactions (AR).

Results A total of 51 patients were treated with Botox.

The distribution by diagnosis was: focal spasticity: 30%. blepharospasm: 24%, bruxism: 20%, hemifacial spasm 18%, others: 8%.

In all cases, the treatment regimen and doses were as recommended in the PI.

The duration of the effect was overall 10 weeks (two weeks less than what appears in the PI), with large variability between patients.

27 patients received 3 doses or more. In 44.4% of them, there was a decrease of efficiency requiring an increase in the dose or the discontinuation of the treatment.

Botox was not effective in 8 patients (15.7%).

AR appeared in 18 patients. 11.8% of the patients had to discontinue treatment due to AR, which differs significantly from the 3.8% showed in the PI.

The most frequent AR were drooping eyelids (19 cases), followed by fever and pain (4 patients in each case), diplopia and eye infection (2 patients in each case).

Conclusions The results obtained in our centre differed from those reported in the PI.

Using the drug in the same conditions as the PI, we obtained a lower duration of response, more AR and a higher percentage of patients had to discontinue treatment due to AR.

No conflict of interest.