I was injected with vallium many times in ER due to spasms. It's usually given IM but if they had a line in would do IV. Never burned. But by that time I usually had 20mg of MS into me also.

IV = 2 minute effect, IM = 10 min come on. The best thing for muscle spasms.

Personally, I dont mind waiting the 30-40 min for an oral dose to take effect - but 10mg IV or IM seems stronger