Smoking, Vaping and Mood: What the Evidence Says

The belief that smoking calms you

Many people describe a cigarette as steadying. The feeling is real. What produces it is worth separating from what the cigarette is doing.

Nicotine reaches the brain within seconds of inhaling. It binds to nicotinic acetylcholine receptors and triggers release of dopamine and other neurotransmitters. In a person who smokes regularly, those receptors have been changed by repeated exposure. Between cigarettes, nicotine levels fall and withdrawal begins. Restlessness, irritability, difficulty concentrating and low mood are part of that withdrawal. The next cigarette relieves those symptoms. The relief is real, and it is relief from a state the previous cigarette produced.

The Royal College of Physicians published a report in 2007, Smoking and mental health, which examined this directly. It concluded that the apparent calming effect of smoking is largely the reversal of nicotine withdrawal, and that smoking does not reduce underlying stress or anxiety.

That distinction matters for anyone trying to work out whether stopping will make their mood worse.

What the trials measured about mood after stopping

Gemma Taylor and colleagues published a systematic review and meta-analysis in BMJ in 2014. It pooled studies that measured anxiety and depression in people before and after stopping smoking. The studies included people with and without psychiatric diagnoses.

The finding was that anxiety and depression scores fell after stopping, and that the size of the fall was similar in people with a psychiatric diagnosis and in people without one. The authors also reported that the effect was comparable in size to the effect of taking an antidepressant for depression in some of the included comparisons.

That finding runs against the belief described above. It is also a group average, not a prediction about any one person. Some people in those studies felt worse before they felt better. Some had a period of low mood that lasted weeks. Averages do not describe individuals.

A separate body of work looks at what happens to mood during the first days and weeks. Irritability, restlessness, low mood, difficulty sleeping and difficulty concentrating are recognised nicotine withdrawal symptoms. The US Surgeon General’s 2020 report Smoking Cessation summarises this literature. Withdrawal symptoms typically peak within the first week and settle over two to four weeks for most people. Some people report low mood lasting longer.

If you are on day three and it is 11pm and you feel awful, that is consistent with what withdrawal looks like. It is not evidence that stopping was a mistake.

Depression while quitting: what to watch for

There is a difference between withdrawal low mood and a depressive episode. Withdrawal low mood usually lifts as nicotine clears and receptors adjust. A depressive episode is more persistent, affects sleep, appetite, interest and energy, and does not necessarily track the withdrawal timeline.

People with a history of depression are more likely to have had depression before, and stopping smoking does not cause a first episode. But some people do report a significant worsening of mood after stopping, and that is worth taking seriously rather than pushing through alone.

Signs that mean contacting a clinician rather than waiting:

• Low mood that is getting worse rather than settling after two to four weeks
• Thoughts of harming yourself, or feeling that others would be better off without you
• Being unable to get out of bed, eat, or look after yourself or dependants
• Feeling detached from reality, or hearing or seeing things others do not
• Drinking or using other substances to manage the mood

In the UK, urgent help is available through NHS 111, option 2, and through your GP. The Samaritans can be reached on 116 123 at any hour. In the US, the 988 Suicide and Crisis Lifeline can be reached by calling or texting 988. These are not overreactions. They are the correct next step.

Smoking and some psychiatric medicines

Smoking does not just affect mood. It affects how the body handles several medicines, including some used in mental health care.

Polycyclic aromatic hydrocarbons in tobacco smoke induce certain liver enzymes, particularly CYP1A2. Those enzymes break down some medicines faster. When a person stops smoking, enzyme activity falls, and blood levels of those medicines can rise.

Clozapine and olanzapine are the clearest examples. The summary of product characteristics for clozapine notes that stopping smoking can increase clozapine blood levels, and that levels should be monitored. Similar considerations apply to some other medicines metabolised by the same pathway.

This is not a reason to keep smoking. It is a reason to tell the clinician who prescribes your medicine that you are stopping, before or as you stop, so the dose can be reviewed. That is a decision for you and your prescriber. This page cannot tell you what to do with any prescription medicine.

Nicotine replacement products do not induce these enzymes in the same way, because the interaction comes from the smoke, not the nicotine. Whether to use one, and which, is a question for a pharmacist, a stop smoking service or your prescriber.

What the options actually are

Different methods have different amounts of trial evidence behind them. That is a statement about evidence, not about what will work for you.

The Cochrane review on hypnotherapy is the honest summary of where that evidence stands. It does not show hypnotherapy is worse than other methods. It shows there is not enough good evidence to say it is better.

If you are on day three

What is likely happening: nicotine has largely cleared from the body, receptor changes are underway, and withdrawal is at or near its peak. Irritability, restlessness, low mood, poor concentration and disturbed sleep are expected. The US Surgeon General’s 2020 report describes this pattern. For most people it eases over two to four weeks.

What is not helpful: being told to stay positive. What is helpful is knowing the timeline, knowing what to watch for, and knowing who to call if mood goes somewhere dangerous.

If you have stopped and feel depressed, the options are not limited to going back to smoking or enduring it. They include contacting a stop smoking service, speaking to a GP or prescriber about mood and about any medicines you take, and using behavioural support. None of those is a promise. They are the things that have been studied.

If you have not stopped yet and are worried about mood, that worry is reasonable and worth raising with a clinician before you set a date, particularly if you have a history of depression or take a medicine affected by smoking.

Whose decision this is

Whether to stop smoking, when, how, and with what support is your decision, made with the clinicians who know your history. This page describes what trials found and what withdrawal looks like. It does not know your circumstances and cannot tell you what to do.

If you take a prescription medicine, the decision about that medicine belongs to you and your prescriber. If your mood is deteriorating, the decision about that belongs to you and a clinician, urgently if needed.

Stopping smoking is not a cure for anything, and no method guarantees it. What the evidence shows is that on average, mood scores improve after stopping, that withdrawal is time-limited for most people, and that several methods have trial support. What it does not show is what will happen to you specifically. That is why the plan is yours, and why the people who can help are named above.