Avoid in individuals with a known allergy or hypersensitivity to black currant, its constituents, or plants in the Saxifragaceae family.

In general, there is a lack of safety information about black currant. Anecdotal information indicates that black currant seed oil may cause diarrhea. Furthermore, some people are not able to tolerate black currant seed oil in capsule form, resulting in diarrhea and other mild gastrointestinal symptoms. The gamma-linolenic acid in black currant may alter blood pressure. Use cautiously in patients with high blood pressure or those taking blood pressure medication.

Avoid in patients with hemophilia or those on anticoagulants (blood thinners) unless otherwise recommended by a qualified healthcare provider, as black currant may enhance the effects of anticoagulants.

Use cautiously in pregnant and breastfeeding women, and in children and the elderly, as their immunity and bodily functions are compromised or underdeveloped.

Use cautiosly in patients taking monoamine oxidase inhibitors (MAOIs), vitamin C supplements, or in patients with epilepsy.

Use cautiously in those with venous disorders, as black currant may increase peripheral blood flow and circulation.

Black currant is not recommended in pregnant or breastfeeding women due to a lack of available scientific evidence; therefore, pregnant women and breastfeeding mothers should avoid the use the black currant seed oil, unless a qualified healthcare provider recommends otherwise.

As a dietary supplement, black currant is available in 500 milligram and 1,000 milligram capsules that typically contain black currant seed oil, vegetable glycerine, and gelatin. Black currant is likely safe when used at a maximum dose of 1,000 milligrams (500-1,000 milligrams are often used per day). Black currant juice is also commercially available and has been taken in doses up to 1.5 liters per day, when mixed with apple juice. Maximum doses of black currant seed oil used in clinical trials range from 4.5-6 grams per day up to eight weeks, although there is no proven effective dose, and safety has not been established. Black currant anthocyanins have been taken in doses of 7.7-50 milligrams for up to two months. Based on some herbal textbooks, there is a lack of reported toxicity concerns with black currant consumed as food or ingested in 500 milligram tablets three times a day.

There is no proven safe or effective dose for black currant in children.

Black currant seed oil may have antibacterial activity; use cautiously with antibiotics and anti-ulcer medications.

Black currant may increase the risk of bleeding when taken with drugs that increase the risk of bleeding, such as warfarin (Coumadin®), clopidogrel (Plavix®), aspirin (Bayer®, Ecotrin®, St John®), enoxaparin (Lovenox®), and dalteparin (Fragmin®).

Black currant may alter blood pressure; use cautiously with blood pressure medications due to possible additive effects.

Black currant may have antioxidant effects. Patients taking other antioxidants should use black currant with caution.

Black currant may have monoamine oxidase inhibitor (MAOI) effects. Use cautiously with anti-depressant medications, such as MAOIs, due to possible additive effects.

Black currant may interact with anti-viral agents. Consult a qualified healthcare professional, including a pharmacist, to check for interactions.

Black currant seed oil may have immune-enhancing effects in the elderly, and should be used cautiously with other agents that affect the immune system.

Black currant may interact with nonsteroidal anti-inflammatory agents (NSAIDS) and COX-2 inhibitors; use cautiously.

Black currant may increase the risk of bleeding when taken with herbs and supplements 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.

Black currant may have monoamine oxidase inhibitor (MAOI) effects. Use cautiously with herbs and supplements with antidepressant activity.

Black currant may interact with anti-inflammatory herbs and supplements; use cautiously due to possible additive effects.

Black currant anthocyanins have antioxidant effects and caution is advised when taking black currant with other agents with antioxidant effects.

Black currant may interact with anti-viral agents. Consult a qualified healthcare professional, including a pharmacist, to check for interactions.

Blackcurrant seed oil (BSO), a rich source of gamma-linolenic acid, may alter blood pressure. Use cautiously in herbs and supplements that may also alter blood pressure, due to possible additive effects.

Black currant seed oil may have immune-enhancing effects in the elderly, and should be used cautiously with other agents that affect the immune system.

Black currant fruit and juice contain rutin and other flavonoids. The flavonoids found in black currant belong to one of two classes: the anthocyanin class or the proanthocyanidin class. Caution is advised when taking black currant with other herbs or supplements containing these flavonoids due to additive effects.

Black currant fruit has a high vitamin C content. Use cautiously with other vitamin C supplements or multivitamin preparations.