A double-blind, placebo-controlled trial of oral human immunoglobulin for gastrointestinal dysfunction in children with autistic disorder.

Researchers gave kids with autism either a daily immunoglobulin pill or a placebo. The pill came in three strengths: 140, 420, or 840 mg. No one knew who got what. The team watched for changes in tummy pain, diarrhea, or behavior for the whole trial.

The study used a double-blind design. That means the families, doctors, and observers all stayed blind to the real drug. This setup keeps bias out of the results.

At every dose, the kids on immunoglobulin looked the same as the kids on placebo. Stomach problems did not get better. Autism behaviors did not shift either. The pill was safe, but it simply did not help.

In short, oral immunoglobulin failed to beat sugar pills on any measure the team tracked.

Lu et al. (2025) pooled 19 later trials of gut treatments and saw clear gains with probiotics. Their meta-analysis includes this 2009 study, so the positive average comes despite these null results. The difference is method: probiotics change gut bacteria, while swallowed immunoglobulin does not.

Piwowarczyk et al. (2020) ran a similar RCT with a gluten-free diet and also found no benefit. Both papers show that single-food or single-pill GI fixes rarely help autism symptoms on their own.

Early reviews like Krause et al. (2002) already warned that immune-based cures lacked proof. This trial confirms that warning with hard data.

If parents ask about immunoglobulin pills, you can share strong evidence: they work no better than placebo. Save time and money by skipping this option. Focus on behavior-analytic strategies or proven gut treatments like probiotics instead. Always pair medical choices with data you can see and graph in your session.