Do not take bupropion if you have taken a monoamine oxidase inhibitor (MAOI) such as furazolidone (Furoxone), isocarboxazid (Marplan), phenelzine (Nardil), rasagiline (Azilect), selegiline (Eldepryl, Emsam, Zelapar), or tranylcypromine (Parnate) in the last 14 days. You should not take bupropion if you have: 
epilepsy or a seizure disorder;
an eating disorder such as anorexia or bulimia;
if you are using a second form of bupropion; or
if you have suddenly stopped using alcohol or sedatives (such as Valium).
Bupropion may cause seizures, especially in people with certain medical conditions. Tell your doctor about all of your medical conditions.
To make sure you can safely take bupropion, tell your doctor if you have any of these other conditions:
a history of head injury, seizures, or brain or spinal cord tumor;
heart disease, high blood pressure, history of heart attack;
kidney or liver disease (especially cirrhosis); or
bipolar disorder (manic depression).

Many drugs can interact with bupropion. Below is just a partial list. Tell your doctor if you are using:
medication used to prevent blood clots, such as clopidogrel (Plavix) or ticlopidine (Ticlid), tirofiban (Aggrastat);
cancer medicine such as cyclophosphamide (Cytoxan, Neosar), doxorubicin (Adriamycin, Doxil), irinotecan (Camptosar), or thiotepa (Thioplex);heart or blood pressure medication such as atenolol (Tenormin), flecainide (Tambocor), metoprolol (Lopressor, Toprol), propafenone (Rythmol), propranolol (Inderal), and others; or
HIV or AIDS medications such as efavirenz (Atripla, Sustiva) or ritonavir (Norvir, Kaletra).
 This list is not complete and there are many other drugs that can interact with bupropion. Tell your doctor about all medications you use. This includes prescription, over-the-counter, vitamin, and herbal products. Do not start a new medication without telling your doctor. You may have a higher risk of seizures if you use certain medications together with bupropion. Tell your doctor about all other medications you use, especially: 
any other antidepressant, or a medicine to treat a psychiatric disorder;
antihistamines that make you sleepy;
asthma medications or bronchodilators;
birth control pills or hormone replacement estrogens;
bladder or urinary medications such as oxybutynin (Ditropan, Urotrol);
antibiotics such as cefdinir (Omnicef), cephalexin (Keflex), ciprofloxacin (Cipro), amoxicillin (Amoxil, Augmentin), penicillin, and others;
diet pills, a stimulant, or ADHD medication such as Adderall or Ritalin;
insulin or diabetes medications you take by mouth;
medication for nausea, vomiting, or motion sickness;
medications to treat or prevent malaria;
medicines to treat Parkinson's disease, restless leg syndrome, or pituitary gland tumor (prolactinoma);
medicines used to prevent organ transplant rejection;
narcotic pain medication;
a sedative such as diazepam (Valium), and others;
a steroid such as prednisone, and others;
street drugs such as "speed" or cocaine;
theophylline (Theo-Dur, Slo-Bid, Bronkodyl Theolair, Respbid); or
ulcer or irritable bowel medications.

It is not known whether bupropion will harm an unborn baby. Tell your doctor if you are pregnant or plan to become pregnant while using this medication. Bupropion passes into breast milk and could be harmful to a nursing baby. You should not breast-feed while you are taking bupropion.

Get emergency medical help if you have any of these signs of an allergic reaction: hives; difficulty breathing; swelling of your face, lips, tongue, or throat.
Report any new or worsening symptoms to your doctor, such as: mood or behavior changes, anxiety, panic attacks, trouble sleeping, or if you feel impulsive, irritable, agitated, hostile, aggressive, restless, hyperactive (mentally or physically), more depressed, or have thoughts about suicide or hurting yourself.
 Call your doctor at once if you have a serious side effect such as: 
seizure (convulsions); severe blistering, peeling, and red skin rash; fever, swollen glands, rash or itching, joint pain, or general ill feeling; confusion, trouble concentrating; orhallucinations, unusual thoughts or behavior.
Less serious side effects may include:
headache or migraine, dizziness, tremors (shaking);sleep problems (insomnia), loss of interest in sex;
nausea, vomiting, constipation, dry mouth;appetite changes, weight loss or gain; or mild itching or skin rash, increased sweating.
This is not a complete list of side effects and others may occur.