The major side effect of the Nexplanon is that some people can have irregular bleeding. Now, that doesn’t happen with everyone, but some people will have bleeding where they bleed for a couple of days and then they don’t bleed for 15-20, then they bleed a couple of days and so on. Or: they may have persistent bleeding for several weeks. Oftentimes if it happens for more than 3 weeks, your provider can give you a sample of birth control pills and then you take it for one month and that will help to resolve the irregular bleeding. Some people have just regular periods and also you may get amenorrhea or no bleeding at all.