The goal of this clinical trial is to evaluate if supplemental zinc can prolong the duration of benefit of botulinum toxin injections in cervical dystonia patients receiving care at the University of Florida.

The main aims are:

1. To evaluate the efficacy of zinc citrate supplementation in prolonging the duration of symptom relief provided by botulinum toxin type A (Botox) injections in cervical dystonia patients.
2. To assess the safety and tolerability of zinc supplementation in this patient population.
3. To analyze the potential influence of zinc supplementation on the quality of life and functional outcomes in cervical dystonia patients receiving Botox.

Researchers will compare zinc citrate to a placebo (a look-alike substance that contains no active drug) to see if zinc works to extend the effects of Botox.

Participants will:

Take zinc citrate or a placebo every day for 3 months, then cross over to the alternative treatment for another 3 months.

Visit the clinic every 3 months for Botox injections, check ups and surveys.

Study Design:

• Randomized, single-blind, crossover placebo-controlled trial.
• Participants: Approximately 20 patients diagnosed with cervical dystonia and currently receiving botulinum toxin (BoNT) type A (Botox) injections at the University of Florida (UF) Movement Disorders Clinic with good response to treatment as determined by treating neurologist will be enrolled into this study. The investigators plan to screen 25 patients to allow for screen failures and withdrawals.
• Intervention: Participants will be randomized to receive either zinc citrate 30 mg supplementation or placebo starting immediately after their scheduled BoNT injection for 3 months. At a follow up BoNT injection, they will receive the alternative treatment for another 3 months. The total observation period is 6 months. Standard time between BoNT injections is 3 months.

The UF Movement Disorders Clinic follows approximately 1,500 cervical dystonia patients a year. The investigators do not anticipate any recruitment challenges.

Participants will be recruited during neurology clinic appointments and screening clinic appointments.

• Patients will receive the same pattern of BoNT injections (muscle selection and dose) during the duration of the study.
• Blood serum levels of zinc and vitamin B12 and complete blood counts (CBCs) will be measured at baseline and at the end of the study. Participants will be sent to UF Health Medical lab for blood draws and sample collection.
• Written informed consent will be obtained from each participant before any study-specific procedures or assessments are performed.

Inclusion Criteria:

• Adults aged 18-89 years.
• Diagnosed with cervical dystonia.
• Receiving regular BoNT type A (Botox) injections for at least six months.

Exclusion Criteria:

• Known allergy or intolerance to zinc.
• Significant comorbidities or concurrent medications that could interfere with study outcomes.
• Pregnant or breastfeeding women.
• Already taking a zinc supplement which would exceed tolerable upper intake level in adults (40 mg elemental zinc per day) with addition of zinc study supplement

Inclusion Criteria:

• Adults aged 18-89 years.
• Diagnosed with cervical dystonia.
• Receiving regular BoNT type A (Botox) injections for at least six months.

Exclusion Criteria:

• Known allergy or intolerance to zinc.
• Significant comorbidities or concurrent medications that could interfere with study outcomes.
• Pregnant or breastfeeding women.
• Already taking a zinc supplement which would exceed tolerable upper intake level in adults (40 mg elemental zinc per day) with addition of zinc study supplement.

Study researchers will be performing the analysis