Blood Draw Risks: Removal of blood by a needle and syringe poses a small risk of pain or bruising at the site of the needle stick, but this is temporary. Some people may experience fainting or dizziness, and there is also a slight risk of infection at the site of the needle stick.

Lumbar Puncture Risks: During the procedure, you may have temporary pain and discomfort in your back. Headache may occur in people who undergo a lumbar puncture. Occasionally, a low-pressure headache may develop, presumably due to leakage of spinal fluid. If this headache persists it may require additional treatment. Uncommonly a blood patch (injection of some of your blood into the lumbar puncture site to patch the spinal fluid leak) may be required. This usually relieves the headache immediately. Although very rare, it is possible that you may have an allergic reaction to the local anesthetic (lidocaine 1%) used for the lumbar puncture. This would cause swelling and a rash on your skin where the anesthetic was injected. Please tell us if you have ever had a reaction to local anesthetic before (such as when you were visiting the dentist). Potential but rare risks of lumbar puncture include infection, damage to nerves in your back, and bleeding that may affect the spinal cord or brain. The risk of these is very small. There is no risk of paralysis.