Just started celexa. Is it true that ssri can cause brain damage? Also, are side effects (drowsiness, low libido) reversible?

No. Celexa can not cause brain damage!!! Side effects are reversible. Sometimes you need time for adjustment to new medications. Discuss this with you doctor. Please, do not panic .
NoBrainDamage/Revers. No not true.Having said that rarely can cause serotonin syndrome when there is accumulation of serotonin in the blood&in worst cases can cause seizures.But it mostly happens when you are taking more than one drug which causes high serotonin level.Incidence with one drug is almost negligible.The side effects are reversible on stoping drug.Do not take any other med without asking your MD or Pharmaci.