Kissing after lip fillers

The lips do swell following injection and can have a few lumps and bumps for up to two weeks as the filler integrates with your lip tissue.  You may also have some degree of bruising which would be telling of injection.  You can do things to diminish swelling and bruising, such as, avoiding any blood thinning agents (one week prior), avoiding alcohol (at least 48 hours), and taking oral Arnica supplements.  Following the procedure, you should ice on and off for 48 hours and you can continue the Arnica for one week following. 

Someone should not be able to tell you have fillers by kissing unless the treatment is extreme.  Four days after filler treatment though you still may have swelling.  It is common after lip fillers and can last up to two weeks.

No, a person may not tell you have had fillers by kissing you. However, you may have some swelling which can last 1-2 weeks after lip fillers. I prefer to use a micro cannula to inject the lips to prevent bruising. Look for a cosmetic dermatologist or plastic surgeon who is an expert in fillers to discuss your desired results and concerns. 
I hope this helps.