When to seek veterinary advice

All cases are different, so it is difficult to specify exactly how long is too long to experience acute gastrointestinal symptoms. Vomiting actual food really shouldn't last more than several hours because either the stomach should be fully emptied (thanks to the vomiting) or because whatever food was in the stomach should have passed into the small intestine. Therefore, if frequent vomiting of actual solid food occurs for more than 8-12 hours, there may be a serious issue. If blood is noticed in either vomit or stool, this can be a sign of internal damage to the GI tract and may potentially be serious. Finally, if diarrhea doesn't improve within three days on bland diet, or if diarrhea isn’t the only symptom, you should consult your pet's veterinarian.
Be aware that more serious and even critical illnesses can initially seem like "food poisoning" to the untrained (and even the trained) eye. Pancreatitis, foreign body obstruction, and Gastric Dilation Volvulus (GDV, more commonly known as bloat) are all life-threatening issues that require veterinary intervention. Additionally, some types of toxicosis (such as antifreeze poisoning) can appear with GI signs. If your pet's GI issues are accompanied by other symptoms such as abdominal pain, vomiting without actually bringing anything up, a visibly swollen belly, restlessness or lethargy, or respiratory difficulty (e.g. continuous panting when it's not hot), there may be more serious cause for concern, and you should consult a veterinarian immediately.
Source: https://www.petcoach.co/