Your injection will take around 15 minutes and you will be able to leave straight away. Having had local anaesthetic administered to the injection area, most patients feel instantly better. This may last up to six hours. You may be asked to fill out a pain diary following your injection. Although rare, there may be some side effects such as swelling, bleeding or skin changes. Our friendly staff will be on hand to explain these to you or alternatively get in touch about post injection advice on +44(0) 203 195 2442. However, if you require medical attention out of clinic hours please go directly to your A&E.