This is a genuinely debated question with substantial evidence on multiple sides—there's no single settled answer, but I can lay out what research and expert opinion generally suggest.
Arguments that social media is harmful
Mental health effects, especially for adolescents:
•Increased rates of anxiety, depression, and loneliness have been linked to heavy use, particularly among teenage girls
•Social comparison (comparing your life/body/achievements to curated posts from others) can erode self-esteem
•Displacement of sleep, in-person socializing, and physical activity
•Algorithmic design optimized for engagement can promote compulsive use and addictive patterns
•Exposure to cyberbullying, harassment, and body-image pressures
Societal effects:
•Misinformation and disinformation spread rapidly and can be hard to correct
•Political polarization—echo chambers and algorithmic amplification of outrage
•Erosion of attention spans and deep reading/thinking
•Privacy concerns and data exploitation
Arguments that social media is helpful
Connection and support:
•Enables maintaining relationships across distance, especially valuable for immigrants, military families, LGBTQ+ youth finding community, and people with rare conditions finding others like them
•Can reduce isolation for people with disabilities or social anxiety who find in-person interaction harder
Information and voice:
•Democratizes publishing—ordinary people, activists, and marginalized groups can reach large audiences without gatekeepers
•Rapid dissemination of emergency information, public health updates, breaking news
•Has fueled genuine social movements (organizing protests, raising awareness)
Economic and creative opportunity:
•Enables small businesses and creators to reach markets cheaply
•New career paths (content creation, influencer marketing)
Why the debate persists
•Effect sizes are contested: some researchers find only small statistical correlations between social media use and poor mental health, while others argue the effects are meaningful, especially for vulnerable subgroups (heavy users, younger teens, girls)
•Causation vs. correlation is hard to disentangle—unhappy people may also use social media differently
•"Social media" isn't monolithic—passive scrolling seems more harmful than active messaging with close friends; platforms differ (image-heavy platforms seem to correlate more with body image issues than text-based ones)
•Individual variation matters enormously—the same platform can help one person and harm another depending on how they use it, their age, existing mental health, and social context
Bottom line
Most researchers land somewhere in the middle: social media itself is a tool, and its net effect depends heavily on how, how much, by whom, and in what context it's used. The clearest area of concern is heavy, passive use among younger adolescents, particularly around social comparison and sleep displacement. The clearest area of benefit is connection for isolated or marginalized populations and information/organizing power.
If you want, I can dig into recent research on a specific angle (teen mental health data, political polarization, effects on adults vs. teens, etc.)—happy to search for current studies if that would help.