Before using this medication, tell your doctor your medical history, especially of: bleeding problems, eye surgery, certain eye problem (glaucoma), heart disease, diabetes, signs of infection near the injection site, urinary tract infection, inability to urinate, muscle/nerve disorders (such as Lou Gehrig's disease-ALS, myasthenia gravis), seizures, trouble swallowing (dysphagia), breathing problems (such as asthma, emphysema, aspiration-type pneumonia), treatment with any botulinum toxin product (especially in the last 4 months).
According to the PREEMPT injection paradigm, 5 units of onabotulinumtoxinA is to be administered to two sites on each side for a total dose of 20 units across four sites in the cervical paraspinal muscle group near the midline. The first injection site is approximately 1 cm left of the midline of the cervical spine and approximately 3 cm (2 fingerbreadths) inferior to the occipital protuberance. The second site is measured approximately 1 fingerbreadth diagonally up at a 45° angle from the first injection. The injections should be administered in the most superficial aspect of the muscle, angling the needle 45° and superiorly. To aid in the placement of the injections, the patient should be positioned upright with the head in a neutral position. If the neck is flexed too far forward, injections may be too deep. Injections that are too low or too deep in this muscle group can lead to muscle weakness and neck pain. Injectors should use a suboccipital approach to ensure that the injection sites are not too low. In addition, a horizontal line can be visualized across the neck, approximately 2 fingerbreadths down from the occipital protuberance, to make certain the injections remain above the line and are not administered too low in the neck. The higher these injections are, the more likely that they will be in the muscle fascial condensation, which will minimize the potential for neck weakness. These injections should not be done below the hairline. Patients who have trigger points in the neck should not be injected at these sites as these are generally areas where muscles may be weakened and injections of onabotulinumtoxinA at these sites might worsen their neck issues.

Spread of toxin effects. The effect of botulinum toxin may affect areas away from the injection site and cause serious symptoms including: loss of strength and all-over muscle weakness, double vision, blurred vision and drooping eyelids, hoarseness or change or loss of voice, trouble saying words clearly, loss of bladder control, trouble breathing, and trouble swallowing.
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