There are vitamins for guinea pigs these are for hamster gerbils rats and mice so go look for vitamins for guinea pigs!

We have 5 hamsters and my daughter expects our bottle of vitamins will last 4 months. She uses 2 drops per water bottle.

By what the Instructions entail, your hamster should not in any means be harmed or killed by this product if it gets in its mouth. However if you are not sure, next to the description tab there is an instruction tab you can click on that gives information on how to give this multivitamin to your small pet. - So it's easier for you let me just give you a short cut.. Lol. -INSTRUCTIONS: Oasis Vita-Drops can be added to the food or the drinking water; whichever is more appropriate and accepted by the small animal. The preferred method of using Oasis Vita-Drops is to add the concentrated liquid supplement to the small animal's daily drinking water (whenever possible, use a sanitary water bottle instead of an open water dish, which can be easily contaminated with debris). However, some small animals may prefer clear non-fortified water, in which case the vitamins may be applied directly to their food. For drinking water: 2 drops per ounce of drinking water. Shake or stir to mix. To insure freshness, change the water at least every 1 to 3 days. For food: Some pocket pets do not drink much water (possibly due to their native arid or desert environment origins.) In these cases, vitamins may be applied or dribbled onto pet's food. Stir 1 or 2 drops of VITA-DROPS into about 1 tablespoon of food, and then layer the fortified food on top of the pet's feed dish. Check to be sure that the vitaminized food has been consumed within 24 hours. If the pet refuses to eat the fortified food, feed the usual plain diet for 3 days and try again. Some pets, such as hamsters, are creature of habit and may not accept the food mixtures immediately. It is very important that the pocket pet not go without food by refusing to eat the fortified food during the training period. Excess dosages should cause no ill effect. Store Oasis Vita-Drops in a cool dry place. May be refrigerated.