Do antidepressants work? What are the side-effects? How long do I need to be on them?

Dr Sarah Kennedy answers commonly asked questions.

Depression can be treated successfully. Antidepressants are proven to help reduce the severity of symptoms, hasten recovery and protect against relapse but they are not the only answer. They work best as part of a varied treatment plan.

What are antidepressants?

Antidepressants work by rebalancing the chemicals in the brain, called neurotransmitters, which are affected by mood, including serotonin and noradrenaline. There are over 30 kinds of antidepressant available in the UK.

Are they addictive?

Antidepressants do not cause addiction as can happen with tranquilisers (or with nicotine, alcohol or heroin) where there is a need to keep increasing the dose to get the same effect.

However, up to a third of people who stop SSRI or SNRI medication do have withdrawal symptoms. These will be mild in most people but sometimes these symptoms can be quite severe. Read the answer to ‘what happens when I stop taking medication?’ to find out more information about withdrawal symptoms.

Do they work?

There are many studies that show that antidepressants do help a large number of people but as with any treatment, they work better for some people and not so well for others. Some people choose not to take medication for their depression. The general position is:

  • Medication can help people with moderate or severe depression. Ideally antidepressants should be given in combination with psychological treatment.
  • Medication is generally not recommended for people with mild symptoms. In this instance exercise, talking therapies and self-help methods are often preferred.

What else do they treat?

Antidepressant medicines, despite the name, are also known to be effective for the following conditions:-

  • Post traumatic stress disorder
  • Anxiety and panic attacks
  • Chronic pain
  • Obsessive compulsive disorder
  • Eating disorders.

If you are unclear why an antidepressant has been suggested for you, ask your doctor.

There seem to be lots of different types of antidepressant. What’s the difference?

Most anti-depressants fall into one of five main categories. Within each of the categories, the individual anti-depressants work in a similar way and have similar side-effects.

The following list includes most of the commonly prescribed anti-depressants with typical side-effects.


Tricyclics were the first anti-depressant to be used, and have been in use since the 1950s. This class of drugs includes:

  • Amitriptyline (Tryptizol)
  • Imipramine (Tofranil)
  • Clomipramine (Anafranil)
  • Lofepramine (Gamanil)
  • Nortriptyline (Allegron)
  • Dosulepin (Prothiaden).

Common problems with Tricyclics include a dry mouth, constipation, a slight tremor, a more rapid heartbeat, sleepiness, and increased appetite. Men may experience difficulties either getting an erection or delayed ejaculation. Tricyclics are very dangerous in overdose.

SSRIs (Selective Serotonin Reuptake Inhibitors)

SSRIs are a type of anti-depressant marketed in the UK since 1989. They block the re-uptake of serotonin into the nerve cell that released it, thereby prolonging its action. These drugs include:

  • Fluoxetine (Prozac)
  • Paroxetine (Seroxat)
  • Citalopram (Cipramil)
  • Sertraline (Lustral).

Particularly in the first week or two SSRIs may cause nausea or even sickness and sometimes they may increase feelings of anxiety. They can cause problems with sexual function in both men and women. Overall the SSRIs are less prone to unpleasant side-effects than the Tricyclics and they are much less dangerous in overdose.

MAOIs (Monoamine Oxidase Inhibitors)

MAOIs are an older type of anti-depressant. MAOIs include:

  • Phenelzine (Nardil)
  • Tranylcypromine (Parnate)
  • Moclobemide (Manerix) is a newer “reversible” MAOI that has less stringent dietary restrictions.

These are now rarely prescribed because of the dietary restrictions they impose. They can cause dangerous increases in blood pressure when taken with cheese, yeast (including beer), red wine and meat that isn’t fresh.

SNRIs (Serotonin and Noradrenaline Reuptake Inhibitors)

These drugs slow the re-uptake of both noradrenaline and serotonin and thus prolong their action.

  • Venlafaxine (Efexor) was the first SNRI
  • Duloxetine (Cymbalta) is the most recently licensed anti-depressant, which was released in Scotland in 2006.

Venlafaxine is similar in its side effects to the SSRIs. It should not to be used in the presence of severe heart problems and it can increase blood pressure which should therefore be monitored. (It can cause weight gain and some problems with sex.)

NASSAs (Noradrenaline and Selective Serotonin Antagonists)

Mirtazapine (Zispin) is similar to the tricylics but has fewer side effects than the older drugs and doesn’t cause problems with sex like the older drugs. It can be quite sedative and can cause weight gain.

Other types of antidepressant

  • Reboxetine (Edronax) is a Selective Noradrenaline Reuptake Inhibitor (NARI).
  • Mianserin and Trazadone (Molipaxin) are related to tricyclics.

Until the 1990s Tricyclics were the most commonly prescribed anti-depressants but now the substantial majority of anti-depressant prescriptions are for SSRIs.

What about side-effects?

Like all medicines, antidepressants can cause side effects. Unfortunately it is not possible to predict who will get these side-effects or how bad they will be however, side-effects can vary considerably between individuals and will usually go away after about 3 weeks.

We’ve listed some potential side effects under each type of antidepressant. For full details on side-effects, read the information sheet provided with your medication. Antidepressants affect people differently so don’t be put off the drug your doctor has prescribed simply because a friend or relation had a problem with it. There is a good chance that you will not have the same problem.

Side-effects from anti-depressants tend to be at their worst in the early stages of treatment. So, if you experience some mild or even moderate side-effects, it may be worth persevering with your treatment to see if the side effects will settle.

Your doctor will be able to advise you on this. The side-effects caused by antidepressants are ones that you will be aware of, such as nausea or headache. Potentially serious side effects that you are unaware of are rare on anti-depressants.

Always tell your doctor if you have any concerns about your medication. They may decide that you need to change the dosage to be more effective or switch to another type of antidepressant to find one that works best for you.

How soon will I feel better?

All antidepressants work slowly. The benefits tend to be felt over weeks rather than days and different symptoms will get better at different times. Most people start to feel some improvement after 2-3 weeks, and the full effect usually takes around 4-6 weeks. It is important to continue taking your anti-depressant so that the full benefit can be felt.

Can I stop taking them when I feel better?

No, you should keep taking your medication for the whole course of treatment as discussed with your doctor. If you stop taking an antidepressant, your original symptoms may return. To reduce the chance of becoming depressed again, they should be taken for at least a further 6 months after you start to feel better and often longer. You should not stop or reduce medication without speaking to your doctor first.

What if I miss a dose?

Never change your dose without checking with your doctor. If you forget a dose, take it as soon as you remember as long as it’s within a few hours of the usual time – if it is not, wait until the following day and take it as you would normally.

Can I still drink alcohol?

It is generally recommended that anyone taking an antidepressant should not take alcohol. The combination of any antidepressant with alcohol may cause drowsiness and increase the risk of falls and accidents. Also, very importantly, drinking alcohol usually makes depression worse. Excessive drinking is especially likely to do this. Read more about the link between depression and alcohol.

Once people are used to their medication, they can sometimes drink alcohol in small amounts without any problems. Avoid alcohol for the first 1-2 months. After this, if you want to drink, try a glass of your normal drink and see how you feel. If it doesn’t make you feel drowsy then it’s probably OK to drink small amounts. It pays to be cautious as alcohol affects different people in different ways, especially when they are taking medication. Never stop your medication because you fancy a drink at the weekend and never drink any alcohol and drive when on an antidepressant.

What if I am pregnant?

It is always best to take as little as possible in the way of medication during pregnancy, especially in the first 3 months, however some mothers do take antidepressants when they are pregnant.

There is some evidence that babies of mums on these medications may experience withdrawal symptoms after birth. Paroxetine (Seroxat) seems to be the antidepressant most likely to do this.

Doctors are advised to consider alternative treatments in pregnancy but for some people, the risk of becoming depressed or remaining depressed may outweigh the possible risks associated with the medication.

This is a very personal decision and is something your doctor and you should discuss together.

Read more about depression during and after pregnancy.


The baby will only get, at most, a small amount of antidepressant from their mother’s milk. Some antidepressants are better than others in this regard. On balance, bearing in mind all the advantages of breastfeeding, it may be best to carry on whilst taking your antidepressant. Again this is a personal decision which should be thoroughly discussed with your doctor.

What happens when I stop taking medication?

Some people do experience withdrawal symptoms when coming off antidepressant medication, but this will vary from person to person; up to one-third of people who stop their SSRI or SNRI have withdrawal symptoms. Usually these are mild but they can be severe for some people. Paroxetine (Seroxat) and Venlafaxine (Efexor) are most likely to be associated with withdrawal problems. The symptoms include:

  • Anxiety
  • dizziness
  • vivid dreams
  • bodily sensations like electric shocks.

Other common symptoms include:

  • nausea
  • stomach problems
  • loss of appetite
  • problems sleeping
  • headaches.

Withdrawal symptoms are typically worse if you stop taking antidepressants suddenly. To reduce the risk of withdrawal symptoms you should plan to reduce you dose slowly over a number of weeks so that your body gets used to the change gradually. Your doctor will talk this over with you, It’s important that you always consult with your doctor when stopping any medication.

Got a question?

If your question isn’t answered here, email Action on Depression call us on 0808 802 2020, or ask your GP. Not many people know that you can also ask your pharmacist questions about your medication. Some pharmacies have consulting rooms where you can ask your pharmacist questions in private. If you are not sure about why you have been suggested an antidepressant or have specific questions about your treatment, it is always important to ask whoever has advised it for you.

Read more about antidepressants and other medication

Royal College of Psychiatrists