A friend of mine had a lip injection put in 2 years ago.now there are small lip bumps and discoloration of lips, but no pain. what might be the possible causes?

That depends...: ...Entirely on what substance was injected. Medical grade fillers like Restylane (dermal fillers) and juvederm dissolve within 3-6 months. Some of the longer-lasting fillers, e.g. Calcium hydroxylapatite, can cause lumps, which is why they are not supposed to be used in the lips. Ditto liquid silicone, which can cause permanent lumps. Your friend will have to find out what it was from whoever did the injecting.

What was injected?: Many materials are offered for lip plumping. Some are safe and some are not. Some are permanent and some are temporary. If the patient has issues 2 years after injection, a permanent injection such as silicone was likely used. There are several methods to improve or resolve the symptoms but it is very important to know what was used in the initial injection.

There are a few: Most products (restylane, perlane, (dermal fillers) juvederm) used to inject the lips are made of natural substances that dissolve over time and are unlikely to persist for two years. If the lips were injected with caha, pmma or silicone then the bumps could be attributable to residual particles or scar tissue. Other causes of lip bumps include varices, traumatic fibromas, sebaceous glands, & salivary glands.

Need more info: There are at least 20 different products that may be introduced into the lips for the purpose of lip augmentation and the treatment will depend on the product employed.