Hi, my 5 year old was prescribed to take 11ml of amoxicillin twice a day(400mg/5ml). he is 43 lbs and i feel like thats too much.

Sounds right: A 5 year old who is 43 lbs is about 20 kg. If he/she has an ear infection, sinus infection or pneumonia, the correct dose is 90 mg per kg per day dosed twice a day. 11 ml twice a day sounds correct. If it is not an ear, sinus, or lung infection he/she is being treated for, please ask the physician who prescribed the medication.

It does but it's ok: Meds for kids are prescribed by weight and need. If this is a urinary tract infection, the med gets concentrated by the kidneys so less can be used.When it involves the mucous in closed spaces like ears/sinuses, the germs are different and today the most common one takes more med to kill.Thirty years ago we could use less, but the germs are getting stronger.