Side Effects of Seroquel (Quetiapine)

Seroquel (quetiapine) is an atypical antipsychotic drug used in the treatment of schizophrenia and the psychotic features of other mental illnesses, and for mood disorders, including bipolar disorder. It works by blocking dopamine receptors in the brain. This minimizes dopamine activity and helps relieve symptoms of these conditions. 

Seroquel can be helpful and effective, but it is also important to be aware of the potential side effects. This includes common symptoms such as constipation, drowsiness, and rapid heartbeat, as well as more serious side effects such as tardive dyskinesia.

Common Side Effects

Along with its therapeutic effects, Seroquel can sometimes cause side effects. Some side effects will have symptoms that you can see or feel. Your doctor may watch for others, such as changes in the lenses of the eyes, by doing certain tests.

Check with your doctor if any of the following common side effects don't go away or are bothersome:

• Abdominal pain
• Abnormal vision
• Constipation
• Decrease in appetite
• Decreased strength and energy
• Dizziness
• Drowsiness
• Dry mouth
• Fast or irregular heartbeat
• Headache
• Increased muscle tone
• Increased sweating
• Indigestion
• Lightheadedness, or fainting, especially when getting up from a lying or sitting position
• Stuffy or runny nose

Serious Side Effects

In some cases, more serious side effects may occur. Some of these include:

• Increased risk of death due to dementia-related psychosis
• Increased risk of suicidal thoughts
• Potential serious weight loss or weight gain

Seroquel can increase the amount of a hormone called prolactin. In some cases, this may interrupt menstruation or breastfeeding. It can also cause decreased sex drive and erectile dysfunction. Long-term exposure to elevated prolactin levels can increase the risk for osteoperosis and bone fractures.

Tardive Dyskinesia

Tardive dyskinesia, a movement disorder, may occur and may not go away after you stop using Seroquel. This was much more common with the older antipsychotic medications, but can very rarely occur with the newer atypical agents such as Seroquel.

Signs of tardive dyskinesia include:

• Chewing or sucking movements
• Grimacing (making faces)
• Lip-smacking
• Puckering or pursing the lips
• Rapid eye blinking
• Tongue protrusion
• Worm-like tongue movements

Medication Interactions

Combining Seroquel with other medications can affect how each medication functions or may lead to increased or decreased side effects. Some of the medications that may interact with Seroquel include:

• Anticonvulsants including carbamazepine
• Antidepressants including fluoxetine
• Antifungal drugs including itraconazole and ketoconazole
• Antihistamines such as chlorpheniramine, diphenhydramine, or brompheniramine
• Barbiturates including phenobarbital
• Benzodiazepines including alazopram, clonazepam, diazapam, and lorazepam
• Herbal supplements such as St. John's wort
• HIV medications including indinavir and ritonavir
• Muscle relaxants including baclofen and metaxalone
• Parkinson's medications including levodopa
• Pain medications including codeine, hydrocodone, morphine, and oxycodone

Seroquel should not be taken with anti-arrhythmic drugs, pentamidine, or methadone. These medications may lead to potentially fatal heart rhythm problems if they are combined with Seroquel.

For this reason, it is important to talk to your prescribing physician about other medications or supplements you are currently taking it. This medication can also lead to increased risks when combined with alcohol or illicit substance, so be sure to talk about any substances you might be using.

When to Seek Help

Another serious but extremely rare side effect that may occur as a result of taking Seroquel is neuroleptic malignant syndrome (NMS).

Stop taking this medicine and get emergency help immediately if the following symptoms of NMS occur, particularly if they occur together:

• Convulsions (seizures)
• Difficult or unusually fast breathing
• Fast heartbeat or irregular pulse
• High fever
• High or low (irregular) blood pressure
• Increased sweating
• Severe muscle stiffness
  

Other Precautions

If you're taking or plan to take Seroquel, keep in mind these precautions:

• The FDA issued a black box warning on all antipsychotic drugs, including Seroquel, due to the increased risk of death in elderly patients with dementia-related psychosis.
• Because Seroquel may cause drowsiness, don't drive or operate machinery until you know how it affects you.
• If you are pregnant or plan to become pregnant or if you are breastfeeding, tell your doctor.
• Don't ever stop Seroquel or change the amount you are taking without your doctor's approval, even if you feel better. This can lead to unwanted effects and problems managing your illness.
• Make sure you don't miss any doses of Seroquel as this can lead to a relapse of the symptoms of your mental disorder.
• If you use alcohol or illegal drugs, tell your doctor since these may make any side effects you experience even worse.
• Make sure to drink plenty of fluids while on Seroquel and avoid becoming overheated.