Aurantii Fructus, Aurantii fructus immaturus, Aurantii pericarpium, Aurantium, Bigarade, Bigarade Orange, Bitter Orange Flower, Bitter Orange Peel, Chao Zhi Ke, Chisil, Citrus amara, Citrus aurantium, Citrus Aurantium Fruit, Citrus bigarradia, Citrus vulgaris, Extrait de Zeste d'Orange, Fleur d'Orange Amère, Flos Citri Auranti, Fructus Aurantii, Fructus Aurantii Immaturus, Green Orange, Kijitsu, Marmalade Orange, Meta-Synephrine, N-Methyltyramine, Naranja Amarga, Neroli Oil, Norsynephrine, Octopamine, Octopamine HCl, Orange Amère, Orange de Séville, Orange Peel Extract, Orange Verte, Seville Orange, Shangzhou Zhiqiao, Sour Orange, Synephrine, Synéphrine, Synephrine HCl, Synéphrine HCl, Synephrine Hydrochloride, Zeste d'Orange Amère, Zhi Ke, Zhi Qiao, Zhi Shi.


Overview Information

Bitter orange is a tree native to Asia. The peel, flower, leaf, fruit, and fruit juice are used to make medicine. Bitter orange oil is made from the peel and/or flower.

People use bitter orange for obesity, athletic performance, indigestion (dyspepsia), and many other conditions, but there is no good scientific evidence to support its use.

Bitter orange contains an active ingredient called synephrine that is similar to ephedra. In 2004, the FDA banned ephedra due to serious effects on the heart. Many weight loss and bodybuilding products contain bitter orange and caffeine, which can cause high blood pressure and increased heart rate in healthy adults. There is concern that using bitter orange might cause heart problems.

Bitter orange (synephrine) is considered a banned substance by the National Collegiate Athletic Association (NCAA).

In foods, bitter orange oil is used as a flavoring agent. The fruit is used for making marmalades and liqueurs such as Triple Sec, Grand Marnier, Cointreau, and Curacao. Because the fruit is so sour and bitter, it is rarely eaten, except in Iran and Mexico. The dried peel of the fruit is also used as a seasoning.

How does it work?

Bitter orange has many chemicals that affect the nervous system. The concentration and effect of these chemicals can change based on the part of the plant used and how it was prepared. These chemicals can squeeze blood vessels, increase blood pressure, and cause the heart to beat faster.


Uses & Effectiveness?

Insufficient Evidence for

  • Anxiety. Some research in adults with acute coronary syndrome shows that inhaling bitter orange flower essential oil for 2 days after leaving the hospital can improve anxiety. Other research shows that taking bitter orange flower by mouth might slightly reduce anxiety symptoms in postmenopausal women with moderate anxiety.
  • Athletic performance. The effects of bitter orange on exercise performance are conflicting. Some early research shows that bitter orange can improve performance during squat exercises when taken with or without caffeine. But it does not seem to reduce feelings of exertion. Other research shows that taking bitter orange, alone or along with a specific pre-workout supplement, once before exercise does not improve weight lifting ability, or cycle or sprint performance, in healthy adults. Taking bitter orange along with the same pre-workout supplement for 8 weeks also does not improve strength in men who weight train.
  • Diabetes. Early research suggests that drinking tea made from the leaves of Indian snakeroot and the fruit of bitter orange for 4 months appears to decrease blood sugar levels in people with diabetes.
  • Indigestion (dyspepsia). Early research suggests that taking a specific product containing bitter orange along with other ingredients (Zhizhu) three times daily for 4 weeks reduces indigestion.
  • Premenstrual syndrome (PMS). Aromatherapy with bitter orange blossom essential oil might improve emotions and mental symptoms of PMS in healthy, young women. But it doesn't seem to improve physical symptoms.
  • Obesity. The effects of bitter orange on weight are unclear. Some research suggests that a combination of bitter orange, caffeine, and St. John's wort might help for weight reduction when used with a low calorie diet and exercise. Taking a specific combination product (Prograde Metabolism, Prograde Nutrition, Lutz, FL) containing bitter orange, raspberry ketone, caffeine, capsaicin, garlic, ginger, black pepper, cayenne pepper, and chromium along with diet and exercise for 8 weeks also seems to improve weight and energy. However, another study found that a combination of bitter orange, caffeine, and several other ingredients did not help people lose weight.
  • Anxiety before surgery. Research suggests that taking bitter orange two hours before surgery reduces anxiety.
  • Ringworm (Tinea corporis). Early research shows that applying bitter orange oil to the skin might help treat ringworm in some people.
  • Jock itch (Tinea cruris). Early research shows that applying bitter orange oil to the skin might help treat jock itch in some people.
  • Athlete's foot (Tinea pedis). Early research shows that applying bitter orange oil to the skin might help treat athlete's foot in some people.
  • Allergies.
  • Bruises.
  • Cancer.
  • Chronic fatigue syndrome (CFS).
  • Colds.
  • Eye swelling.
  • Headaches.
  • Gas (flatulence).
  • Insomnia.
  • Liver and gallbladder problems.
  • Nasal congestion.
  • Nerve and muscle pain.
  • Stimulating appetite.
  • Stimulating the heart and circulation.
  • Stomach and intestinal upset.
  • Other conditions.
More evidence is needed to rate the effectiveness of bitter orange for these uses.

Side Effects

Side Effects & Safety

When taken by mouth: Bitter orange is LIKELY SAFE when taken in the amounts found in food. But bitter orange is POSSIBLY UNSAFE when taken in the larger amounts used as medicine. Bitter orange, taken by itself or with stimulants such as caffeine or caffeine-containing herbs, might increase the risk for high blood pressure, fainting, heart attack, stroke, and other severe side effects. There are reports that bitter orange can trigger headaches, including migraine and cluster headaches, in some people.

When applied to the skin: Bitter orange essential oil is POSSIBLY SAFE. Bitter orange can cause sensitivity to the sun. Wear sunblock outside, especially if you are light-skinned.

When inhaled: Bitter orange essential oil is POSSIBLY SAFE when inhaled as aromatherapy.

Special Precautions & Warnings:

Pregnancy and breast-feeding: during pregnancy when used in the amounts found in food. However, it is POSSIBLY UNSAFE when taken by mouth in medicinal amounts. There isn't enough reliable information to know if bitter orange is safe to use when breast-feeding. Stay on the safe side and stick to food amounts during pregnancy or breast-feeding.

Diabetes: Some evidence suggests that bitter orange may interfere with blood sugar control in patients with type 2 diabetes. Use with caution and monitor blood sugar levels closely.

High blood pressure: Some studies suggest that bitter orange, especially in combination with caffeine, can increase blood pressure in healthy people. Other studies have found no such blood pressure elevation. To date, there haven't been any studies looking at the effect of bitter orange on blood pressure in people who already have high blood pressure. Don't take a chance. Avoid using bitter orange, especially in combination with stimulants such as caffeine, if you have high blood pressure.

Glaucoma: Bitter orange might worsen glaucoma. Avoid using it if you have this condition.

Heart disease: Using bitter orange, especially in combination with caffeine or other stimulants, might increase the risk of serious side effects in people with a particular heart problem called "long QT interval syndrome" (named after the wave pattern made by an electrocardiogram.

Irregular heartbeat (heart arrhythmia): Some studies suggest that bitter orange, especially in combination with caffeine, can increase heart rate in healthy people. Other studies have found no such effect on heart rate. So far, there have been no studies of the effect of bitter orange on people who have an irregular heartbeat. Avoid using bitter orange, especially in combination with stimulants such as caffeine, if you have an irregular heartbeat.

Surgery: Bitter orange acts like a stimulant, so it might interfere with surgery by increasing heart rate and blood pressure. Stop taking bitter orange at least 2 weeks before a scheduled surgery.



Major Interaction

Do not take this combination

  • Medications for depression (MAOIs) interacts with BITTER ORANGE

    Bitter orange contains chemicals that stimulate the body. Some medications used for depression can increase these chemicals. Taking bitter orange with these medications used for depression might cause serious side effects including fast heartbeat, high blood pressure, seizures, nervousness, and others.

    Some of these medications used for depression include phenelzine (Nardil), tranylcypromine (Parnate), and others.

  • Midazolam (Versed) interacts with BITTER ORANGE

    The body breaks down midazolam (Versed) to get rid of it. Bitter orange can decrease how quickly the body breaks down midazolam (Versed). Taking bitter orange along with midazolam (Versed) might increase the effects and side effects of midazolam (Versed).

Moderate Interaction

Be cautious with this combination

  • Caffeine (Excedrin, Anacin, Vivarin, and others) interacts with BITTER ORANGE

    Bitter orange is a stimulant. Caffeine is also a stimulant. In combination, they can increase blood pressure and cause the heart to beat rapidly. This can cause serious adverse effects such as heat attack and stroke.

  • Dextromethorphan (Robitussin DM, and others) interacts with BITTER ORANGE

    The body breaks down dextromethorphan (Robitussin DM, others) to get rid of it. Bitter orange might decrease how quickly the body breaks down dextromethorphan (Robitussin DM, others). Taking bitter orange along with dextromethorphan (Robitussin DM, others) might increase the effects and side effects of dextromethorphan (Robitussin DM, others).

  • Felodipine (Plendil) interacts with BITTER ORANGE

    Felodipine (Plendil) is used to lower blood pressure. The body breaks down felodipine (Plendil) to get rid of it. Bitter orange might decrease how quickly the body gets rid of felodipine (Plendil). Taking bitter orange along with felodipine (Plendil) might increase the effects and side effects of felodipine (Plendil).

  • Indinavir (Crixivan) interacts with BITTER ORANGE

    Indinavir (Crixivan) is used to treat HIV/AIDS. The body breaks down indinavir (Crixivan) to get rid of it. Bitter orange might decrease how quickly the body breaks down indinavir (Crixivan). Taking bitter orange along with indinavir (Crixivan) might increase the effects and side effects of indinavir (Crixivan).

  • Medications changed by the liver (Cytochrome P450 3A4 (CYP3A4) substrates) interacts with BITTER ORANGE

    Some medications are changed and broken down by the liver.

    Bitter orange might decrease how quickly the liver breaks down some medications. Taking bitter orange along with some medications that are broken down by the liver can increase the effects and side effects of some medications. Before taking bitter orange, talk to your healthcare provider if you are taking any medications that are changed by the liver.

    Some medications changed by the liver include lovastatin (Mevacor), ketoconazole (Nizoral), itraconazole (Sporanox), fexofenadine (Allegra), triazolam (Halcion), and many others.

  • Medications that can cause an irregular heartbeat (QT interval-prolonging drugs) interacts with BITTER ORANGE

    Bitter orange might increase the speed of your heartbeat. Taking bitter orange along with medications that can cause an irregular heartbeat might cause serious side effects including heart arrhythmias.

    Some medications that can cause an irregular heartbeat include amiodarone (Cordarone), disopyramide (Norpace), dofetilide (Tikosyn), ibutilide (Corvert), procainamide (Pronestyl), quinidine, sotalol (Betapace), thioridazine (Mellaril), and many others.

  • Stimulant drugs interacts with BITTER ORANGE

    Stimulant drugs speed up the nervous system. By speeding up the nervous system, stimulant medications can make you feel jittery and speed up your heartbeat. Bitter orange might also speed up the nervous system. Taking bitter orange along with stimulant drugs might cause serious problems including increased heart rate and high blood pressure. Avoid taking stimulant drugs along with bitter orange.

    Some stimulant drugs include diethylpropion (Tenuate), epinephrine, phentermine (Ionamin), pseudoephedrine (Sudafed), and many others.



The appropriate dose of bitter orange depends on several factors such as the user's age, health, and several other conditions. At this time there is not enough scientific information to determine an appropriate range of doses for bitter orange. Keep in mind that natural products are not always necessarily safe and dosages can be important. Be sure to follow relevant directions on product labels and consult your pharmacist or physician or other healthcare professional before using.

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