Quetiapine is used to treat and prevent the return of symptoms in Schizophrenia and other mental health related conditions. Learn how to use the medication, its common side effects, special precautions to watch out for, and more.

What is this medication for?

Quetiapine belongs to a class of medications known as atypical (second-generation) antipsychotics. It is used to treat and prevent the return of symptoms in Schizophrenia and other mental health related conditions such as:

• Hearing, seeing or sensing things that are not real
• Having mistaken beliefs
• Being overly suspicious
• Uncontrolled anger

It can be used to treat symptoms in bipolar disorder such as:

• Very high mood
• Irritability
• Increased activity and energy
• Depression/low mood

It can also be used to treat (in combination with other medications) symptoms of depression (low mood) such as:

• Feeling sad 
• Feeling hopeless or useless
• Feeling bad about yourself 
• Thoughts of ending your life
• Poor sleep, energy or appetite

Quetiapine may be used for other conditions. Check with your healthcare professional if you are unsure why you are given this medication.

How should I take/use this medication?

• Take your medication according to the instructions stated on the medication label.
• Quetiapine may be taken with or without food. If you are taking Quetiapine XR (extended-release) tablet, swallow the tablet whole. Do not split, crush or chew the tablet.
• Do not stop taking or adjust the dose of this medication without checking with your doctor.
• Quetiapine needs to be taken regularly for a few weeks before you can feel its full benefits. You should not stop taking this medication even if you do not feel better at the beginning. Continue to take this medication even after you feel better to prevent your symptoms from returning.
• Do check with your doctor on how long you will have to be on this medication.

What should I do if I forget to take/use this medication?

• If you forget to take a dose, take it as soon as you remember. However, if more than half of the time to the next dose has passed, skip the missed dose and take the next dose at your usual timing.
• For example, for a medication to be taken two times daily at 8am and 8pm, and you missed your first dose at 8am, skip the first dose if it is after 2pm, and take your second dose at the usual timing at 8pm. Do not take two doses to make up for the missed dose.

What precautions should I take?

Inform your healthcare professional if: 

• You are allergic to this medication or any of the other ingredients of this medication
• You are pregnant, planning to become pregnant, or breastfeeding. If you are pregnant and/or breastfeeding, your doctor would have discussed the potential benefits and side effects with you and should you have further questions or concerns, do consult your doctor.
• You are taking any other medications (including those that can be bought without a prescription), supplements, traditional Chinese medicine and herbal products. Some of them may affect how this medication works or cause serious drug interactions.
• You have diabetes. Quetiapine may sometimes worsen blood sugar control in diabetes. Maintain regular check-ups with your doctor.
• You have or have ever had:
  • Drug allergies
  • Medical conditions such as:
    • Blood disorders, irregular heartbeat or heart problems; kidney, liver or thyroid disease, breast cancer, stroke
    • High or low blood pressure, high cholesterol/fats in the blood, seizures (fits), dementia, history of blood clots, Parkinson’s disease, swallowing difficulties

What are some common side-effects of this medication?

The mentioned side effects generally affect up to 10% of patients. 

• Drowsiness or feeling tired
  • Avoid driving or taking part in activities that require concentration
  • Discuss with your doctor if you can take your medication at a different time of the day
• Nausea, vomiting
  • Take the medication with or after food
  • Take small but more frequent meals, and avoid fatty or spicy food
• Constipation
  • Drink more water (if you do not have any fluid restriction), eat more high-fibre foods, and exercise regularly
  • Speak to your doctor or pharmacist if you need medication to help with your constipation
• Dizziness
  • Get up slowly from a sitting or lying down position
• Dry mouth
  • Chew sugar-free gum, suck on sugar-free hard candies or ice chips, sip water regularly
• Increase in appetite, weight gain
  • Exercise regularly and eat a healthy and balanced diet

Most of the side effects listed here will improve with time. Speak with your doctor if any of them continues, worsens or affects your daily life.

What are some rare but serious side-effects that I need to seek medical advice immediately?

The symptoms of a drug allergy include one or more of the following: 

• Swollen face/eyes/lips/tongue
• Difficulty in breathing
• Itchy skin rashes over your whole body

Rarely this medication may cause:

• Seizures (fits)
• Confusion, high fever, severe muscle stiffness, irregular blood pressure (signs and symptoms of neuroleptic malignant syndrome)
• Muscle movement side effects (extrapyramidal side effects) – do speak to your doctor for further management. Examples include:
  • Uncontrollable shaking of limbs (tremors)
  • Muscle stiffness and spasms (such as in the face, neck and back), difficulty in speaking or swallowing, twitching, or upward rolling of eyes (symptoms of dystonia)
  • Restlessness or need to keep moving constantly (akathisia)
  • Uncontrollable movements (such as in the face, tongue, jaw or other parts of the body) (tardive dyskinesia)
• Blurred vision
• Difficulty in passing urine (urinary retention)
• Fast or irregular heartbeat, fainting episodes (signs and symptoms of an abnormal heart beating rhythm (prolonged QTc interval))
• Fever, chills, sore throat and/or mouth ulcers that do not go away (symptoms of blood dyscrasias)
• Severe chest pain, difficulty breathing, or severe pain or swelling in either of the legs (symptoms of venous thromboembolism)
• Excessive hunger, unusual increase in thirst or passing large amount of urine (symptoms of high blood sugar)
• Increased prolactin hormone in the body (hyperprolactinemia):
  • Changes in menstrual cycle in females (Irregular or stopping of menstrual periods) and/or
  • Abnormal breast swelling, soreness or secretion (in both men and women)
• Sudden weakness or numbness in the face, arms or legs, and speech or vision problems (signs and symptoms of stroke)
• Changes in weight, restless or weak, hair thinning, low mood, eye or neck swelling, trouble with cold, menstrual changes (signs and symptoms of hypothyroidism)

If you experience any of these symptoms, you should stop your medication and see your healthcare professional immediately.

IMPORTANT:

In some cases, particularly in young people below the age of 25 years, this medication may cause the following changes to a person’s mental condition, especially in the first few weeks of treatment or during dose changes:

• New or worsening thoughts of harming yourself or ending your life
• Worsening agitation, restlessness, violent behaviour, or
• Other changes in mood or behaviour

Please inform your doctor as soon as possible, or for your family or caregiver to inform your doctor if you are unable to seek treatment on your own.

Do not stop taking this medication on your own without discussing with your doctor.

It is important to note that your doctor has prescribed this medication as he/she feels you will benefit more from taking this medication over the possible risks that it may cause. Most people have taken this medication without having any of such problems.

What food or medication should I avoid when I take this medication?

Avoid drinking alcohol while taking Quetiapine as it can cause excessive sleepiness.

Avoid grapefruit juice/products while taking Quetiapine, as the amount of Quetiapine in the body may be increased, and this may increase risk of side effects.

How should I store this medication?

Store in a cool and dry place, away from direct sunlight. Keep this medication away from children. 

How should I throw away this medication safely?

Pack this medication into a trash bag and seal it tightly before throwing into the rubbish chute or bin.

Disclaimers

Please take note that the above is not a complete list of all possible side effects. If you have any concerns about your medication or if you have other side effects that you think are caused by this medication, please consult your doctor or pharmacist.

If you take more than the recommended dose, please seek medical advice immediately. The information provided on this page does not replace information from your healthcare professional. Please consult your healthcare professional for more information.

This article is jointly developed by members of the National Medication Information workgroup. The workgroup consists of cluster partners (National Healthcare Group, National University Health System and SingHealth), community pharmacies (Guardian, Unity and Watsons) and Pharmaceutical Society of Singapore. The content does not reflect drug availability and supply information in pharmacies and healthcare institutions. You are advised to check with the respective institutions for such information.

Last updated on Aug 2023