When to expect results from a new medication

Each one can have a different timetable. Find out in advance what you should expect, and then track your symptoms.

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When your doctor prescribes a new medication, you may expect to start feeling the effects right away. But some drugs can take time to make a difference. "It depends on how quickly your body absorbs the medication, how your body distributes it, and how your body breaks down or metabolizes it," says Laura Carr, a pharmacist at Harvard-affiliated Massachusetts General Hospital.

Giving it time

Some medications start working on the first day. These include drugs that treat high blood pressure, like the beta blocker metoprolol (Toprol, Lopressor), which slows down the heart and reduces the force of its contractions; or H2 blockers such as famotidine (Pepcid) and ranitidine (Zantac), which treat heartburn by blocking the stomach's acid-secreting cells from making acid.

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