Phentoin 100mg Tablet can be used alone or in combination with other medications It can be taken with or without food Your doctor will determine the appropriate dosage for you which may be gradually increased until your condition is stable It may take several weeks for this medication to take effect so it is important to take it regularly to obtain the full benefit Unless instructed by your doctor do not discontinue use even if you feel well Stopping the medication abruptly may result in an increase in seizures or worsening of bipolar disorder symptoms The most common side effects of Phentoin 100mg Tablet include skin rashes headaches nausea difficulty sleeping dizziness and drowsiness Most side effects are temporary and will subside but if they persist or bother you inform your doctor There may be ways to prevent or reduce these side effects Before taking this medication inform your doctor if you have kidney or liver problems meningitis depression or experience suicidal thoughts Additionally inform your healthcare team about all other medications you are taking as some may interact with Phentoin 100mg Tablet including contraceptive pills If you are pregnant or breastfeeding Phentoin 100mg Tablet may be taken if necessary but the dosage may need to be adjusted If this medication causes drowsiness or dizziness it is advisable to avoid driving or riding a bicycle You may also require frequent blood tests to monitor your response to the medication