Hi,
I took my dog into the vets this AM as she had been vomiting since the early hours of the morning, but more worryingly had obvious stomach pain and was seeming very uncomfortable. after a couple of checks we are going for 'wait n see' and he gave her an anti emetic (sp?) and a painkiller injection.Does anyone know how long before the effects wear off? She seemed much happier as soon as we got home and is quite bright now but I don't know how long until I know if she is actually better or it is just the drugs helping. I forgot to ask when I was in there!

thanks

How is your dog now?

Is this a one off or something new?  How is her stool?
Causes of vomiting are varied..

What Might Cause A Sudden, or Acute, Episode of Vomiting?

Bacterial infection of the gastrointestinal tract
Diet-related causes (diet change, food intolerance, ingestion of garbage)
Foreign bodies (i.e. toys, bones, pieces of chewies) in the gastrointestinal tract
Intestinal parasites
Acute kidney failure
Acute liver failure or gall bladder inflammation
Pancreatitis
Post-operative nausea
Ingestion of toxic substances
Viral infections
Certain medications or anesthetic agents
Bloat
Heatstroke
Car sickness
Infected uterus
Vomiting that occurs sporadically or irregularly over a longer period of time can be due to stomach or intestinal inflammation, severe constipation, cancer, kidney dysfunction, liver disease or systemic illness.

The key thing is to pinpoint the cause....if it is a "one off " has she eaten something harmful?
Is the vomit yellow? ,this suggests  pancreatis ..maybe a food too rich?
If there is blood in the vomit,there may be an infection..eg helicobacter etc
.. if the stomach is empty for too long a dog may vomit yellow bile....it helps to feed a couple of bonio type biscuits as supper to fill the stomach .
The list is long...the wait and see protocol is to see if the dog recovers fast or not...if this reoccurs your vet will test for parasites,a blockage ,and probably quiz you about the dogs eating habits.
Hope she feels better today.

http://dogs.helium.com/how-to/13103-how-to-assess-a-dog-vomit

I'd speak to your vet as only they know exactly what they gave you and how it works.