According to the CDC, most sexually active individuals should get tested for STIs at least once a year, with specific recommendations for increased testing frequency for those under 25, individuals with multiple partners, or those engaging in high-risk sexual behaviors; this includes getting tested before starting a new relationship. 

KEY POINTS ABOUT STI TESTING FREQUENCY:

Young adults:
Sexually active women under 25 should be tested annually for chlamydia and gonorrhea. 

High-risk individuals:
People with multiple partners, new partners, or those engaging in high-risk sexual activities should get tested more frequently, potentially every 3-6 months. 

Men who have sex with men (MSM):
Should be tested for syphilis, chlamydia, and gonorrhea at least once a year. 

Pregnancy:
All pregnant women should be tested for syphilis, HIV, hepatitis B, and hepatitis C early in pregnancy. 

IMPORTANT FACTORS TO CONSIDER:

Recent exposure:
If you’ve had a new sexual partner or unprotected sex recently, consider getting tested sooner. 

Symptoms:
If you experience any symptoms associated with an STI, seek testing immediately.