Carbamazepine Adverse Effects
Carbamazepine can cause serious and potentially life-threatening adverse effects including severe skin reactions, blood disorders, hepatotoxicity, and neurological toxicity, requiring careful monitoring and genetic screening in high-risk populations. 1
Common Adverse Effects
Neurological Effects
- Dizziness, drowsiness, and unsteadiness (most common side effects) 1
- Ataxia and problems with coordination 1
- Double vision 1
- Taking medication at bedtime can minimize these effects 2
Gastrointestinal Effects
Serious Adverse Effects
Dermatological Reactions
- Serious skin rashes that may lead to death, including Stevens-Johnson syndrome and toxic epidermal necrolysis 1
- Higher risk in people of Asian descent, particularly carriers of HLA-B*15:02 2, 1
- Most likely to occur within the first four months of treatment 1
- Signs include:
- Skin rash, hives
- Sores in mouth
- Blistering or peeling of skin 1
Hematological Effects
- Rare but serious blood disorders including aplastic anemia and agranulocytosis 1, 3
- Symptoms include:
- Fever, sore throat, infections that persist
- Easy bruising
- Red or purple spots on body
- Bleeding gums or nosebleeds
- Severe fatigue or weakness 1
- Higher risk in elderly patients 4
Hepatic Effects
- Liver problems occur in approximately 2% of patients 2, 4
- Most hepatic disorders occur within the first 2 months of treatment 4
- Signs include:
- Yellowing of skin or eyes
- Dark urine
- Right-sided abdominal pain
- Easy bruising
- Loss of appetite 1
Cardiac Effects
- Irregular heartbeat
- Fast, slow, or pounding heartbeat
- Shortness of breath
- Feeling lightheaded
- Fainting 1
Neuropsychiatric Effects
- Suicidal thoughts or actions (approximately 1 in 500 patients) 1
- Depression, anxiety, agitation
- Irritability, aggression, or violent behavior
- Insomnia 1
- Lowered seizure threshold 2
Risk Factors and Monitoring
High-Risk Populations
- Asian ancestry (especially Han Chinese) for Stevens-Johnson syndrome 2, 1
- Elderly patients for blood dyscrasias and liver reactions 4
- Alcohol users for serious skin reactions 4
Recommended Monitoring
- HLA-B*15:02 screening before initiating treatment in patients of Asian descent 2, 5
- Complete blood count with platelets 5
- Liver function tests 5
- Monitoring should be more frequent during the first 2 months of treatment when most serious reactions occur 4
Special Considerations
Pregnancy
- Carbamazepine may harm the unborn baby 1
- For women with mild conditions, consider discontinuing treatment prior to or during pregnancy 2
- Pregnant women should register with the North American Antiepileptic Drug Pregnancy Registry 1
Drug Interactions
- Carbamazepine is a potent inducer of CYP3A4 and can accelerate the metabolism of many other drugs 6
- May reduce effectiveness of oral contraceptives 1
- Inhibition of carbamazepine metabolism by certain drugs can lead to toxicity 6
Management of Adverse Effects
- Do not stop carbamazepine suddenly as this can cause serious problems 1
- For mild neurological side effects, taking medication at bedtime may help 2
- For patients who cannot tolerate side effects, alternative treatments such as oxcarbazepine or other sodium channel blockers (lamotrigine, topiramate, phenytoin) should be considered 2
- Immediate medical attention is needed for signs of serious skin reactions, blood disorders, or liver problems 1
By understanding these potential adverse effects and implementing appropriate monitoring, the risks associated with carbamazepine therapy can be minimized while maintaining its therapeutic benefits.