The picture-taker hits send. The threats begin. Take a breath; there are things you can do.

1. First of all, don’t pay the scammer.

According to experts, it won’t help. “Paying rarely stops the sextortion,” said Susan Kennedy, the director of community of engagement at the National Center for Missing and Exploited Children.

2. Block the harasser, but don’t delete your account.

“You don’t want to fully delete your profile, because there will be information on there that law enforcement can use,” Ms. Kennedy said. “Those messages can be helpful in the investigation.”

3. Tell law enforcement.

The National Center for Missing and Exploited Children runs an anonymous tip line to report incidents both online (report.cybertip.org) and via telephone (800-843-5678). To reach the center via email: gethelp@necmec.org.

The F.B.I. also has a tip line (800-CALL-FBI; or online at tips.fbi.gov) as does Department of Homeland Security: 877-4-HSI-TIP.

4. You can get a photo taken down.

“It is really important to know it’s not a hopeless situation,” Ms. Kennedy said. “We used to tell kids once something is out on the internet it’s out there forever — it’s not true.”

If an explicit or sexually compromising image is posted online, there are ways to get it removed via software like Take It Down, a program developed by the center that works by assigning a digital fingerprint to a photo that enables tech companies to seek out and remove it. It can be used anonymously: takeitdown.ncmec.org.

Ms. Kennedy also urges parents to begin conversations with children about the risk of online sextortion as early as elementary school; she’s seen sextortion victims as young as 8 years old, she said.

“It’s important for parents to talk to kids about this for two reasons: First of all they will know that there is help if this does happen to them,” Ms. Kennedy said. “But the other reason kids don’t come forward is they don’t think that there is anything they can do about it.”