Stinging Nettle: Toxicity. Adverse Reactions

Insufficient reliable evidence is available.

Adverse Reactions

One report states that gastrointestinal discomfort, allergic reactions, urticaria, pruritus, oedema and decreased urine volume are possible.

Clinical studies in BPH with herbal combinations containing nettle have found only 0.72% to 3.7% experience mild adverse effects.

URTICARIA DUE TO STINGING NETTLE

A frequent cause of contact urticaria is skin exposure to the stinging nettle. The urticaria is accompanied by a stinging sensation lasting longer than 12 hours. Part of the immediate reaction to nettle stings is due to histamine introduced by the nettle. It has also been found that both hair and plant extracts of nettle contain high levels of leukotrienes B4 and C4, besides histamine, which add to the irritant effects.

Significant Interactions

Controlled studies are not available; therefore, interactions are based on evidence of activity and are largely theoretical and speculative.

DIURETIC MEDICINES

Potentiated effects are theoretically possible observe — patients taking this combination.

ANTIHYPERTENSIVE MEDICINES

Additive effects are theoretically possible observe— patients taking this combination.

FINASTERIDE

Additive effects are theoretically possible, although the interaction may be beneficial.

Contraindications and Precautions

People with known sensitivities or allergies to stinging nettle should use this herb cautiously. If symptoms of BPH worsen, seek professional advice.

Pregnancy Use

Use of nettle during pregnancy is contraindicated because of its effects on hormones (WHO 2003).