I have always had to gear myself up to submit to these blood tests and put them off. My doctor is understanding and has now prescribed Valium to help me through the experience.
But I was wondering isn't there anything else that would actually lessen the little pain of the needle going in--could I use something like ambesol that people use for gum pain? Or is there anything else?
Second related question. Of course I also have to fast. But I heard somewhere that drinking plenty of water pumps up the vein to make easier entry. Is that true? And is it allowed because of the instructions to fast?
You could try ambesol. It might work, but it's used for gums which do not have a thick epidermal layer that prevents the absorption of medication, so it's likely to be much less effective. There are creams with local anesthetics in them called EMLA that can work if placed at least 45 minutes prior to puncture. But even that is not perfect. I small local anesthetic subdermal injection just prior to venapuncture can totally numb the site, but it requires a small needle prick and the local anesthetic does burn for a second when it is injected.
Water should not interfere tremendously with the blood tests. However, don't over do it. hydrate aggressively the night before, and then maybe one glass of water prior to going to the lab. they will likely want to check glucose, so no sweets (nothing with sugar or carbs).
In honesty, phlebotomists (the workers who draw blood for labs) aren't typically willing to inject local anesthetics and are more than likely not going to have any EMLA on hand (although they might). You would need a Rx from an MD to get this so if its super important to you, you may try asking your doc first if he/she is willing to write you a script for it.