A hamster should be fed a diet which meets its nutritional requirements and an inadequate diet can lead to health problems. Mixes prepared for other animals may not meet the needs of a hamster, and some mixes may actually harm the hamster. Therefore it is important to feed a mix specifically designed for hamsters.
An inadequate diet can result in fur loss, wasting, and lethargy. If diet deficiency is suspected the hamster's diet should be changed and vitamin drops should be added to the hamster's water. If the hamster does not improve within a week or worsens or shows other symptoms veterinary advice should be sought.
Once the hamster has been transferred to a good diet the hamster should improve within a week or two.