Poison Control is a free, confidential service staffed around the clock by specially trained professionals. In the United States the number is 1-800-222-1222, and an online guidance tool is also available.
It is the right call for accidental double doses, a child getting into medicine, or uncertainty about whether an amount taken is dangerous. Emergency services should be called instead if the person has collapsed, is having a seizure, cannot be woken, or is struggling to breathe.