Kiwi allergy is one of the more common allergies among fruits and caution is advised. There are numerous reports of allergy and cross-sensitization with kiwi and birch pollen, banana, avocado, chestnut, melon, fig, nuts, poppy seeds, sesame seeds, rye grain, hazelnuts, flour, latex-containing plants, and grasses. Asthma, rash, "hives," swelling and anaphylaxis have been reported.

The most common adverse effect is allergy to kiwi, which may or may not clinically manifest in symptoms ranging from local mouth irritation to anaphylaxis. Urticaria ("hives") and angioedema (swelling) due to allergy, and allergic contact dermatitis have been reported. Oral Allergy Syndrome (OAS), which includes itching and tingling with or without edema (swelling) of the lips, mouth, and tongue has been observed after consuming kiwi. Acute pancreatitis has also been reported.

Kiwi is known to have high levels of vitamin C, E, potassium and serotonin and may be capable of altering triglyceride levels. Nausea, vomiting, diarrhea, dysphagia (difficulty swallowing), and collapse have also been reported.

Kiwi is not recommended in pregnant or breastfeeding women due to a lack of available scientific evidence.

There is no proven effective dose for kiwi. As an antioxidant, doses between 150 and 500 milliliters of kiwi fruit juice have been used. For cardiovascular health, two or three kiwi fruits per day for 28 days have been studied. For energy enhancement, doses between 500 and 1,200 milliliters of kiwi fruit juice (Actinidia sinensis planch, ASP) have been studied.

One study reported beneficial effects on wheezing and other respiratory conditions in children from consuming between one and seven kiwi fruits per week.

Based on preliminary laboratory data, kiwi may have antifungal activity and therefore have an additive effect when taken with other antifungals.

Kiwi may increase the risk of bleeding when taken with drugs that increase the risk of bleeding. Some examples include aspirin, anticoagulants ("blood thinners") such as warfarin (Coumadin®) or heparin, anti-platelet drugs such as clopidogrel (Plavix®), and non-steroidal anti-inflammatory drugs such as ibuprofen (Motrin®, Advil®) or naproxen (Naprosyn®, Aleve®).

Kiwi has a high serotonin concentration. Selective serotonin reuptake inhibitors (SSRIs) alter the levels of serotonin in the body usually by increasing them. Therefore, theoretically, kiwi and SSRIs may have a synergistic effect on serotonin levels.

Consumption of kiwi fruit may lower blood triglycerides.

Based on preliminary data, kiwi may have antifungal activity and therefore have an additive effect when taken with other antifungals.

Based on preliminary data, kiwi may have antioxidant activity and therefore have an additive effect when taken with other antioxidants.

In theory, kiwi may increase the risk of bleeding when also taken with other products that are believed to increase the risk of bleeding. Multiple cases of bleeding have been reported with the use of Ginkgo biloba, and fewer cases with garlic and saw palmetto. Numerous other agents may theoretically increase the risk of bleeding, although this has not been proven in most cases.

Substantial amounts of lutein and zeaxanthin are present in kiwi fruit. Caution is advised when taking lutein supplements.

Theoretically, kiwi may have an effect on the amount of potassium in the body because kiwi is rich in potassium.

Theoretically, kiwi is associated with an increased amount of serotonin. Kiwi plus herbs/supplements that alter serotonin levels may have an effect on the levels of serotonin in the body.

Consumption of kiwi fruit may lower blood triglycerides.

Kiwi may increase the amount of vitamin C in the body because this fruit is rich in vitamin C. Based on urinary measurements, vitamin C status improved in athletes supplemented with Actinidia sinensis planch drink in one study.

Theoretically, kiwi may have an effect on the amount of vitamin E in the body because kiwi is rich in vitamin E.