I'm not sure but i think i may have accidentally took an extra 100 mg atenolol several hours apart. will i be ok?

Most Probably- Yes: Watch for anxiety, nervousness headache, unusual tiredness and even trouble sleeping. If you experience worsening difficulty breathing, chest pain, change in vision, fast heart beats or tingling/numbness/ cold hands /feet go to er. Atenolol last in the system for about 6-7 hours. Any of the above symptoms should be improving over time. Drink plenty of water to help eliminate the drug. Take care.