I use 100 mg quetiapine for insomnia , is it safe taking it for long time? thanks

Talk to your doctor: Quetiapine is not a sleep aid, but often gets prescribed for insomnia due to its common side effect of sedation. It's primarily for treating schizophrenia and bipolar disorder. It has potential serious side effects (especially if used long term): it can negatively impact on your lipids, glucose control, weight or cause movement disorders. There are probably better long-term options.

Management & safety: of medications require ongoing medication review with prescriber based on individual circumstances as they change over time. Seroquel at 100 mg is a low dose and should be safe long term though must watch for weight gain, blood sugar, and lipid issues. Sleep hygiene measures are best for developing healthy sleep and meds are useful based on underlying conditions and while developing good sleep.