How long does saline solution last when injected to test out an appearance similar to that of filler?

Saline injections do not mimic fillers as the fillers are moldable, shapeable, and are injected at various depths with viscosity which saline doesn't have so you can get shape or contour.  I suggest going to an expert, as no expert would suggest that saline can represent a true filler.  Best, Dr. Emer.

Thank you for your question.  Saline lasts for a day or so in the face, but the inflammation from the needle poke to get the saline in the right spots will last for 3-4 days (or longer depending on the technique).  One thing to keep in mind is that saline injection can give you an idea of what it will look like, but don't expect the exact same results because fillers don't exactly replicate the appearance of tissue swelling from trauma.  All the best!

Saline lasts 24 hours or less. Some surgeons will inject saline into the skin to "test" the area before using a filler. This is not common. In fact, it is rarely done. But, there are some circumstances that it can be useful. In general, saline tests the distensibility of the skin (how much it can stretch) and if it is bound down (as is seen with scars). Skin that is NOT distensible or that is bound down, will not do as well and other options would be considered. Saline does not mimic the results of a filler as they have different properties (the filler is more viscous and saline is thin).