SSRIs and SNRIs

What SSRIs and SNRIs are

SSRIs (selective serotonin reuptake inhibitors) and SNRIs (serotonin and norepinephrine reuptake inhibitors) are two widely prescribed classes of antidepressant medicine. Both reduce the reuptake, or reabsorption, of certain chemical messengers by nerve cells, leaving more available in the gap between them. SSRIs mainly affect serotonin, while SNRIs affect both serotonin and norepinephrine.

Both classes are used for depression and several anxiety-related conditions, and both appear in psychology courses as examples of how medicines act at the synapse. Research on how antidepressants work continues, and current understanding is more complex than the older “chemical imbalance” explanation.

Talking to a professional

Choosing between medicines, or deciding whether medication is suitable at all, depends on a person’s symptoms, health, other medicines, past responses and preferences. That decision belongs with a qualified prescriber, and stopping or switching antidepressants should only be done with medical guidance.

Relevant professionals include primary care doctors (GPs), psychiatrists and pharmacists. Psychologists and licensed therapists provide evidence-based talking therapies that are often used alongside or instead of medication.

Before an appointment, it can help to note down your questions, what you have noticed and any medicines you already take. It is reasonable to ask about the options available, what the research says about them and what happens next. Good clinicians welcome questions and explain things in plain language.

Learn more

To learn more, see our pages on depression, anxiety disorders and the difference between psychiatrists and psychologists. Our guide to types of mental health professionals explains who does what.