Antidepressant medicines

Antidepressants are medicines that ease the symptoms of depression. They are also used for anxiety, some kinds of pain and other problems. They are very common. In one U.S. survey from 2015 to 2018, about 1 in 8 adults had taken one in the past month. Among adults 60 and older, it was nearly 1 in 5.¹⁴

These medicines can help a lot, but they are not quick fixes. They take weeks to work, they can have side effects, and some need extra care in later life. This page explains the main types in plain words so you can talk with your doctor with confidence. It does not give doses.

How antidepressants work

Your brain uses chemical messengers to pass signals between nerve cells. Two of them are serotonin and norepinephrine. Most antidepressants change how much of these messengers are available. Experts still do not fully know why this eases depression, or why it takes weeks.

Depression is more complex than a simple "chemical imbalance." To learn more, see what causes depression. Antidepressants still help many people, even though the exact way they work is not fully known.

The main types

Doctors group antidepressants by how they act on the brain. The newer groups, listed first, are used most often because they tend to have fewer side effects.¹

The 2022 VA/DoD depression guideline suggests starting with an SSRI, an SNRI, bupropion, mirtazapine, trazodone, vilazodone or vortioxetine. It found no proof that any one of these works better than the rest. It advises against tricyclics and MAOIs as a first choice, but they remain options later.²

Some newer combination medicines exist too. For example, Auvelity combines bupropion with dextromethorphan.⁴ When depression does not get better after several tries, other treatments are available. See when depression doesn't get better.

How long they take to work

Antidepressants work slowly. Most people need 4 to 8 weeks to feel the full effect.¹ Early on, you may notice better sleep, appetite, energy or focus before your mood lifts.¹

The first medicine does not always work. If you have little or no change after a fair trial, your doctor may raise the dose, switch to a different medicine, add talk therapy, or add a second medicine.² Needing to try more than one is common. It does not mean you have failed.

After you feel well, guidelines advise staying on the medicine for at least six months to lower the chance that depression comes back.² Some people stay on it much longer, especially after several episodes. Your doctor can help you decide. For the full picture of options, see treatment for depression.

Common side effects

Many side effects are mild and fade over the first few weeks.¹ Common ones include:^1,3,9

• Upset stomach, nausea or diarrhea
• Headache
• Feeling sleepy, or having trouble sleeping
• Sweating or dry mouth
• Sexual problems, such as lower desire or trouble reaching orgasm

Your doctor usually starts low and goes slow. Taking the medicine at a different time of day or with food can sometimes help. Ask before changing how you take it.¹

Some medicines, like trazodone and mirtazapine, can make you drowsy. Alcohol can make this worse. Do not drive until you know how the medicine affects you.^5,6

Extra cautions for older adults

Antidepressants can be safe and helpful in later life. But age changes how the body handles medicine, and many older adults take several medicines. Talk with your doctor about these risks.

Falls. The CDC lists antidepressants, including SSRIs and tricyclics, among medicines linked to falls.¹⁰ Dizziness when standing up is common with trazodone.⁶ Stand up slowly, use night lights, and tell your doctor about any fall. See preventing falls.

Low sodium in the blood (hyponatremia). SSRIs and SNRIs can lower the salt level in the blood. Older adults, people who take water pills (diuretics) and people who are dehydrated face the highest risk.³ Early signs can be headache, trouble focusing, memory problems, confusion, weakness and unsteadiness. These can lead to falls.³ Your doctor may check a blood test, especially in the first weeks.

Bleeding. SSRIs and SNRIs can raise the risk of bleeding. The risk goes up with aspirin, pain relievers like ibuprofen or naproxen (NSAIDs), warfarin and other blood thinners.³ Tell your doctor about unusual bruising, nosebleeds or black stools.

Heart rhythm. Citalopram can change heart rhythm at higher doses. The FDA set a lower top dose for people over 60.¹¹ Trazodone and tricyclics can also affect heart rhythm.^6,7

Older medicines. MedlinePlus advises that most older adults should not take amitriptyline because other medicines are safer.⁷ Tricyclics can also cause confusion.⁷

For more, see depression in later life and medicines that can affect mood and memory. A yearly "brown bag" review, where you bring all your pills to the doctor or pharmacist, is a good habit.

Medicine mix-ups to avoid

Serotonin syndrome is rare but can be life-threatening. It can happen when an antidepressant is mixed with other medicines or supplements that raise serotonin. Examples include triptans (migraine medicines) and St. John's wort.¹ Signs include agitation, muscle twitching, high fever, and big swings in blood pressure.¹

St. John's wort is an herbal product some people take for low mood. It can interact with antidepressants and weaken many other medicines, including warfarin and birth control pills.¹³

MAOIs can cause dangerous reactions with many medicines and with foods high in tyramine, such as aged cheeses and smoked or spoiled meats.⁸ They also stay in the body for weeks after stopping.⁸ Never take an MAOI and an SSRI at the same time.³

The warning about suicidal thoughts in young people

All antidepressants in the U.S. carry a boxed warning. That is the FDA's strongest kind of warning. It says these medicines can raise the risk of suicidal thoughts and actions in children, teens and young adults up to age 24.^3,4,5

In short studies of children and teens, about 4 in 100 people on an antidepressant had suicidal thoughts or behavior. On a placebo (a look-alike pill with no medicine), it was about 2 in 100. No one died by suicide in those studies.¹⁵ In adults 25 and older, the risk did not go up. In adults 65 and older, it went down.³

Untreated depression is also dangerous. So this warning means watch closely, not "avoid." The risk is highest in the first few months and after any dose change.⁴ Families should watch for new or worse depression, agitation, panic, trouble sleeping, anger, or talk of self-harm. Call the doctor right away if you see these.^3,15

Bipolar disorder. In people with bipolar disorder, an antidepressant alone can set off mania (an extreme high with little sleep and racing thoughts). Doctors should ask about bipolar disorder before starting one.³ See getting diagnosed with bipolar disorder.

Stopping safely

Many people feel well and want to stop. That is a fair goal. But stopping suddenly can cause withdrawal symptoms (sometimes called discontinuation symptoms).^3,12 These can include:^3,9

• Dizziness, nausea or headache
• Irritability, anxiety or low mood
• Trouble sleeping
• Strange feelings in the body, like brief "zaps"

NICE, the UK health guideline group, advises lowering most antidepressants slowly. The steps should get smaller as the dose gets lower. The plan should fit the person, with regular check-ins.¹² Withdrawal can last weeks or even months for some people. Symptoms can start late.¹²

Withdrawal can feel like depression coming back. Signs that point to withdrawal include symptoms that start soon after a dose cut, feel different from your old depression, or are new.¹² If this happens, your doctor may pause, make smaller cuts, or go back to the last dose for a while.¹²

Questions to ask your doctor

Education only. This page is general information written from the sources listed. It is not medical, legal or financial advice and does not replace a doctor, therapist or lawyer who knows your situation. How we write and check pages.