Aspirin low-dose is a reduced dosage version of regular strength aspirin. Regular strength aspirin is 325 mg. Aspirin low-dose is below 100 mg., typically 81 mg. If you need aspirin for pain relief or treating a fever, you should take the regular strength, unless recommended otherwise by your doctor. Aspirin low-dose is taken on a daily basis to reduce the risk of heart attack and stroke. You should not take regular dose aspirin on a long-term, regular basis because of the risk of serious side effects from chronic use.