Drug Action: How SSRIs Work

SSRI drugs are often used to treat depression. Depression is associated with low levels of serotonin, a chemical that acts on certain brain cells involved in thoughts and mood. Nerve cells in the brain constantly release and reabsorb the chemical serotonin. SSRIs reduce the rate of reabsorption, resulting in higher levels of serotonin in the brain.

Before the drug

Nerve impulses stimulate the release of serotonin from nerve endings in brain cells. The serotonin stimulates other brain cells. It is then reabsorbed and stored in the nerve endings, ready to be released again.

After the drug

The drug blocks some of the reabsorption sites on the nerve endings, reducing the amount of serotonin that is absorbed. This leaves higher levels of serotonin available in the brain, which increases brain cell stimulation.

From the 2010 revision of the Complete Home Medical Guide © Dorling Kindersley Limited.

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