SIDE EFFECTS: Headache, nausea, vomiting, diarrhea, dizziness, drowsiness, numbness/tingling, or trouble sleeping may occur. If any of these effects persist or worsen, notify your doctor or pharmacist promptly. Remember that your doctor has prescribed this medication because he or she has judged that the benefit to you is greater than the risk of side effects. Many people using this medication do not have serious side effects. Tell your doctor right away if any of these unlikely but serious side effects occur: loss of coordination, fainting, swollen glands (lymph nodes), butterfly-shaped rash on the nose/cheeks, vision changes (e.g., blurred vision, double vision), uncontrolled side-to-side eye movements (nystagmus). A small number of people who take anticonvulsants for any condition (such as seizure, bipolar disorder, pain) may experience depression, suicidal thoughts/attempts, or other mental/mood problems. Tell your doctor right away if you or your family/caregiver notice any unusual/sudden changes in your mood, thoughts, or behavior including signs of depression, suicidal thoughts/attempts, thoughts about harming yourself. Severe (rarely fatal) blood disorders (aplastic anemia, pancytopenia) and liver problems have occurred with ethotoin. Discuss the risks and benefits with your doctor before starting ethotoin. Tell your doctor right away if any of these rare but very serious side effects occur: unusual bleeding/bruising, symptoms of infection (fever, chills, persistent sore throat), symptoms of anemia (tiredness, pale skin/fingernails, fast heartbeat), liver problems (e.g., severe stomach/abdominal pain, unusual weakness/tiredness, pale stools, dark urine, yellowing eyes/skin). A very serious allergic reaction to this drug is rare. However, seek immediate medical attention if you notice any symptoms of a serious allergic reaction, including: rash, itching/swelling (especially of the face/tongue/throat), severe dizziness, trouble breathing. This is not a complete list of possible side effects. If you notice other effects not listed above, contact your doctor or pharmacist. In the US - Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088 or at www.fda.gov/medwatch. In Canada - Call your doctor for medical advice about side effects. You may report side effects to Health Canada at 1-866-234-2345.

PRECAUTIONS: Before taking ethotoin, tell your doctor or pharmacist if you are allergic to it; or to other hydantoins (e.g., phenytoin); or if you have any other allergies. This product may contain inactive ingredients, which can cause allergic reactions or other problems. Talk to your pharmacist for more details. This medication should not be used if you have certain medical conditions. Before using this medicine, consult your doctor or pharmacist if you have: blood problems (e.g., anemia), liver disease. Before using this medication, tell your doctor or pharmacist your medical history, especially of: kidney disease, lupus, folate or vitamin B12 deficiency (megaloblastic anemia). This drug may make you dizzy or drowsy. Alcohol or marijuana can make you more dizzy or drowsy. Do not drive, use machinery, or do anything that needs alertness until you can do it safely. Avoid alcoholic beverages. Talk to your doctor if you are using marijuana. Older adults may be more sensitive to the side effects of this drug, especially dizziness, loss of coordination, or fainting. These side effects can increase the risk of falling. During pregnancy, this medication should be used only when clearly needed. It may harm an unborn baby. However, since untreated seizures are a serious condition that can harm both a pregnant woman and her unborn baby, do not stop taking this medication unless directed by your doctor. If you are planning pregnancy, become pregnant, or think you may be pregnant, immediately talk to your doctor about the benefits and risks of using this medication during pregnancy. Since birth control pills, patches, implants, and injections may not work if taken with this medication (see also Drug Interactions section), discuss reliable forms of birth control with your doctor. The use of anti-seizure drugs during pregnancy may increase the risk of bleeding in the newborn baby. Your doctor may order vitamin K injections for you/your newborn. This medication passes into breast milk. Consult your doctor before breast-feeding.

DRUG INTERACTIONS: Drug interactions may change how your medications work or increase your risk for serious side effects. This document does not contain all possible drug interactions. Keep a list of all the products you use (including prescription/nonprescription drugs and herbal products) and share it with your doctor and pharmacist. Do not start, stop, or change the dosage of any medicines without your doctor's approval. Some products that may interact with this drug are: blood thinners (e.g., warfarin), nisoldipine, orlistat, drugs that can cause low blood counts (e.g., cancer chemotherapy), other anti-seizure medications (e.g., phenytoin, valproate). This medication may decrease the effectiveness of hormonal birth control such as pills, patch, or ring. This could cause pregnancy. Discuss with your doctor or pharmacist if you should use additional reliable birth control methods while using this medication. Also tell your doctor if you have any new spotting or breakthrough bleeding, because these may be signs that your birth control is not working well. Ethotoin is very similar to phenytoin. Many medications interact with phenytoin. It is not known whether the same drugs interact with ethotoin. However, it is very important to tell all your doctors and pharmacists of all the medications you use, including ethotoin. Tell your doctor or pharmacist if you are taking other products that cause drowsiness such as opioid pain or cough relievers (such as codeine, hydrocodone), alcohol, marijuana, drugs for sleep or anxiety (such as alprazolam, lorazepam, zolpidem), muscle relaxants (such as carisoprodol, cyclobenzaprine), or antihistamines (such as cetirizine, diphenhydramine). Check the labels on all your medicines (such as allergy or cough-and-cold products) because they may contain ingredients that cause drowsiness. Ask your pharmacist about using those products safely.

OVERDOSE: If someone has overdosed and has serious symptoms such as passing out or trouble breathing, call 911. Otherwise, call a poison control center right away. US residents can call their local poison control center at 1-800-222-1222. Canada residents can call a provincial poison control center. Symptoms of overdose may include: unusual eye movements, unsteadiness, loss of consciousness.