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Zyban (bupropion)

Dr Roger Henderson
Reviewed by Roger HendersonReviewed on 29.04.2024 | 8 minutes read

Zyban (bupropion hydrochloride) is a prescription-only, non-nicotine medication that a doctor can prescribe to help you stop smoking. This is best achieved by using Zyban if you are fully committed to giving up smoking, alongside motivational support such as taking part in the NHS Stop Smoking service.

Zyban cannot be used with Champix (varenicline) or nicotine replacement therapy like gums, lozenges or sprays. It is not licensed for those under 18 or women who are pregnant or breastfeeding, and caution is suggested with certain medical conditions and medications.

How does Zyban work?

The exact mechanism of action that Zyban works to reduce cravings for cigarettes is not known; however, bupropion is an inhibitor of the neuronal uptake of certain chemical messengers in the brain, such as noradrenaline (norepinephrine), serotonin and dopamine. It works to reduce the pleasurable effects of smoking and nicotine, most likely linked to the release of dopamine, which gives the reward effect you feel if you do have a cigarette. It also reduces the usual withdrawal symptoms of anxiety and irritability.

Treatment schedule

Zyban is usually given as a 7 to 12 week treatment plan, starting one week before the planned quit day, while they are still smoking. This is because it takes around one week to reach the target level of Zyban in the blood. It is recommended that the planned quit date should be within the first 2 weeks of treatment with Zyban.

The starting dosage is to take one 150mg tablet daily for the first 3 days, thereafter increasing to one 150mg tablet to be taken twice a day (preferably at least 8 hours apart).

The tablets can be taken with or without food, however, they should be swallowed whole and not crushed, divided, or chewed, as this may affect the absorption rate of the drug, and may potentially lead to an increased risk of adverse effects including seizures. Those with liver or kidney impairment may require a lower dose regimen.

The treatment should be discontinued if the patient has not been able to stop smoking within the 7 to 12 week treatment plan, and should be assessed for other strategies to stop smoking instead.

Some patients who have been able to quit and stay off smoking by the 12 week-mark may benefit from additional continued therapy after a closer reassessment by their prescriber on an individual basis, alongside continued counselling and support as necessary.

Common side effects

Like all medicines, this medicine can cause side effects, although not everyone gets them.

Difficulty sleeping is the most common side effect of Zyban, affecting more than 1 in 10 people. This may be minimised by adjusting the timing of the second dose to an earlier time in the evening.

Other common side effects (typically affecting up to 1 in 10 people) include:

  • feeling depressed, anxious or agitated
  • difficulty concentrating
  • feeling shaky (tremor)
  • headache
  • feeling sick (nausea) or in some cases vomiting
  • stomach pain or other stomach upset such as constipation
  • changes in the taste of food, dry mouth
  • fever, dizziness, sweating
  • skin rash (sometimes due to an allergic reaction) or itching

Other less common side effects (typically affecting 1 in100 people) include:

  • an increase in blood pressure
  • visual disturbances
  • tinnitus
  • feeling weak
  • chest pain
  • a rapid heartbeat

Some people taking Zyban have developed high blood pressure which needs treatment. If you already have high blood pressure, it can become worse. This is more likely if you are also using nicotine patches to help you stop smoking.

Please note that these are not all the side effects of Zyban. For a full list see the leaflet inside your medicine packet.

In case of overdose or taken too much you should contact your pharmacist, doctor or urgent out of hours advice as soon as possible by calling 111, or attend your Emergency Department.

Who should I avoid Zyban?

Zyban is not suitable for anyone under the age of 18. Before starting Zyban you should let your doctor know if you have any kidney, liver or heart conditions, or suffer with any mental health conditions, as Zyban might not be the best option in some circumstances.

Zyban is also not recommended patients for the following groups of patients:

  • those with a seizure disorder
  • those with a current or prior diagnosis of bulimia or anorexia nervosa
  • patients undergoing detox or abrupt discontinuation of alcohol, benzodiazepines barbiturates, and antiepileptic drugs
  • patients taking certain medications to treat psychiatric disorders

Pregnancy and breastfeeding

Zyban is not usually recommended if you are pregnant. Some studies have reported an increase in the risk of birth defects, particularly heart defects, in babies whose mothers were taking Zyban. However, other studies have not seen this increase, and it is not known if these defects are due to the use of Zyban. The ingredients of Zyban can pass into breast milk. You should ask your doctor or pharmacist for advice before taking Zyban if you are breastfeeding.

Continuing to smoke during pregnancy increases the risk of miscarriage, some birth defects, premature birth, low birth weight, and some pregnancy complications. Your doctor may be able to recommend a different option to Zyban, such as nicotine replacement therapy (NRT).


Some of the side effects of Zyban, such as feeling dizzy or light-headed, may affect your concentration and judgement. If you are affected, do not drive or operate machinery.

Alcohol use

Some people find they are more sensitive to alcohol while taking Zyban. Your doctor may suggest you do not drink alcohol while you are taking Zyban, or try to drink as little as possible. If you have an alcohol dependency, don’t just stop suddenly, because that may put you at risk of having a fit. Speak with your doctor to discuss the best treatment strategy.

Taking other medicines

Tell your doctor or pharmacist if you are taking, have recently taken or might take any other medicines, including medicines you bought without a prescription. Patients taking a group of drugs called reversible MAOIs such as linezolid or intravenous methylene blue should not take Zyban at the same time or within 14 days of stopping these medicines.

There may also be a higher than usual risk of fits or seizures with Zyban, if you take:

  • medicines for depression or other mental health problems
  • theophylline for asthma or lung disease
  • tramadol, a strong painkiller
  • medicines against malaria
  • stimulants or other medicines to control your weight or appetite
  • steroids (except creams and lotions for eye and skin conditions)
  • antibiotics subgroup called quinolones
  • some types of antihistamines mainly used to treat allergies, that can cause sleepiness
  • medicines for diabetes
  • alcohol

Some medicines can affect how Zyban works or make it more likely that you’ll have side effects. These include:

  • some medicines used for treatment of depression and you may experience mental status changes (such as agitation, hallucinations, coma), and other effects, such as body temperature above 38°C, increase in heart rate, unstable blood pressure, and exaggeration of reflexes, muscular rigidity, lack of coordination and/or gastrointestinal symptoms (such as nausea, vomiting, diarrhoea)

  • medicines for Parkinson’s disease (such as levodopa, amantadine or orphenadrine)

  • carbamazepine, phenytoin or valproate, to treat epilepsy or some mental health problems

  • some medicines used to treat cancer (such as cyclophosphamide, ifosphamide)

  • ticlopidine or clopidogrel, mainly used to treat heart disease or stroke

  • some beta-blockers (such as metoprolol), mainly used to treat high blood pressure

  • some medicines for irregular heart rhythm (such as propafanone, flecainide)

  • ritonavir or efavirenz, for treatment of HIV infection

If you take any medicines on this list, check with your doctor. Your doctor will weigh up the benefits and risks to you of taking Zyban, or may decide to change the dose of the other medicine you are taking.

Zyban may make other medicines less effective, such as tamoxifen used to treat breast cancer, or digoxin for heart rhythm. If this applies to you, tell your doctor. It may be necessary to change to an alternative treatment to help you quit smoking.

Zyban with herbal remedies or supplements

There is very little information about taking herbal remedies and supplements whilst taking Zyban and the effects this can have, since they are not tested in the same way as medicines. It may be worth speaking to your pharmacist about whether to avoid using them whilst taking Zyban.

When should I see my doctor or pharmacist?

If you experience any of the common side effects, that are not settling down after a few weeks, or are unbearable, you should speak to your stop smoking adviser, doctor or pharmacist, and discuss with them about alternative strategies to help you stop smoking instead.

You should also speak to your doctor straight away if feel agitated, depressed or have thoughts about hurting yourself.

When to seek urgent medical help

Seek urgent medical help if you are experiencing chest pain, or any of the less common or rarer side effects (see product information leaflet insert of the packet for more details), such as:

  • fits or seizures – affect about 1 in 1,000 people
  • twitching, muscle stiffness, uncontrolled movements, or problems with walking or coordination
  • fainting or feeling faint when you stand up suddenly.
  • feeling restless or aggressive
  • sensing or believing things that are not true (delusions) or severe suspiciousness (paranoia)
  • feeling unreal or strange (depersonalisation) or seeing or hearing things that are not there (hallucinations).
  • strange dreams (including nightmares)
  • loss of memory
  • tingling or numbness
  • urinary incontinence (involuntary urination or leakage of urine)
  • worsening of psoriasis (thickened patches of red skin)
  • your skin or the whites of your eyes turning yellow (jaundice), an increase in liver enzymes on a blood test or hepatitis
  • changes in blood sugar levels

In addition, severe allergic reactions that affect the mouth and other parts of the body can be life-threatening. Other rashes together with joint and muscle pains may indicate systemic lupus erythematosus, which requires urgent medical attention.

You should ring the emergency services by calling 999 immediately or attend your Emergency Department.

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Dr Roger Henderson
Reviewed by Roger Henderson
Reviewed on 29.04.2024
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