Thanks for your question on Healthcare Magic.
I can understand your concern.
Food
poisoning causes
gastritis,
vomiting and
diarrhea.
Vomiting and diarrhea causes loss of fluid and electrolytes (sodium and potassium) from the body.
Gastritis and vomiting cause less appetite and decreased oral intake.
So overall patient is dehydrated and sodium, potassium depleted.
These can cause all the symptoms like headache, generalized
body ache, muscle and join pain, giddiness, sleepiness etc.
Best treatment for this is oral rehydration solution (ORS) and fruit juices. So ask your fried to drink plenty of fluids orally including ORS (2 liters per day) and fruit juices. Better not to take hot, spicy and outside food.
Don't worry, your friend will improve with all these in 2-3 days.
Hope I have solved your query. I will be happy to help you further. Wishing good health to your friend. Thanks.