Reviewed: Dabaghzadeh F, Khalili H, Dashti-Khavidaki S, Abbasian L, Moeinifard A. Ginger for prevention of antiretroviral-induced nausea and vomiting: a randomized clinical trial. Expert Opin Drug Saf. 2014;13(7):859-866.

Antiretroviral therapy used to treat human immunodeficiency virus (HIV) infection produces nausea in 42% to 57% of patients and vomiting in 28% to 32% of patients. Although the nausea and vomiting disappear over time, they adversely affect treatment adherence. Pharmaceutical treatments are available to decrease these reactions; however, these treatments have their own adverse side effects, can produce drug-drug interactions, and may be cost prohibitive.

Clinical studies have demonstrated that ginger (Zingiber officinale, Zingiberaceae) rhizome can alleviate certain gastrointestinal symptoms associated with pregnancy, recovery from surgery, and chemotherapy. The purpose of this randomized, double-blind, placebo-controlled study was to evaluate the efficacy of ginger for the prevention of antiretroviral-induced nausea and vomiting.

Patients (n=115, aged 18 to 65 years) with HIV participated in this study conducted at the HIV clinic of Imam Khomeini Hospital in Tehran, Iran. Excluded patients had current presentation or a history of peptic ulcers, dyspepsia, or nausea and vomiting; were using antiemetic or antacid products; had a history of ginger hypersensitivity; or were taking concomitant anticoagulant therapy. All patients were treated with antiretroviral drug combinations — either efavirenz plus lamivudine and zidovudine, or lopinavir/ritonavir and didanosine.

Patients received placebo or 500 mg powdered ginger rhizome (Goldaroo Pharmaceutical Company; Isfahan, Iran) twice per day, 30 minutes before each dose of antiretroviral drugs for 14 days. (According to the article, Goldaroo’s products undergo “periodical analysis and quality control” under the supervision of the Iran Ministry for Health’s Drug and Food Control Laboratory, although no additional analytical details were provided.) Patients were instructed not to take any additional treatment for gastrointestinal (GI) problems such as nausea and vomiting. Any patient requiring pharmaceutical treatment for GI problems was withdrawn from the study. Patients also were instructed not to change their meal regimens. Severity of nausea was assessed with a visual analog scale, and patients were monitored daily by telephone.

At baseline, both groups had similar characteristics and laboratory data. Significantly more patients in the placebo group (90.2%) than in the ginger group (56.9%) had some degree of nausea (P=0.001). Also, the ginger group had a significantly lower frequency of mild, moderate, and severe nausea than the placebo group (P=0.02, P=0.04, and P=0.001, respectively). Placebo-treated patients reported an occurrence of at least one episode of vomiting significantly more often (47.1%) than the ginger-treated patients (9.8%) (P=0.01). Ginger was well tolerated. The authors conclude that ginger was effective at decreasing nausea and vomiting associated with antiretroviral therapy, but it was more effective in the prevention of vomiting.

A peer reviewer of this Research Review noted that there are several key limitations of this study: First, there was poor characterization and study design to assure the placebo comparison was meaningful, particularly the description of allocation concealment, masking of the ginger and placebo (it is easy to both smell and taste ginger root), and the evaluation of the success of masking, which is usually accomplished by asking participants to guess which treatment they received at the end of the study. Without these elements, the placebo comparison may not be valid, and study results might be biased in favor of the ginger intervention. The second limitation was the researchers’ decision to withdraw patients requiring further anti-emetics and not including those “treatment failures” in an intention-to-treat analysis.

It also should be noted that ginger can inhibit cytochrome CYP enzymes and may alter the efficacy and safety of protease inhibitors used to treat HIV. Future studies need to evaluate other doses of ginger, whether starting ginger therapy prior to starting antiretroviral therapy would increase efficacy, and whether there is an optimal time in the day to take the ginger therapy.

—Heather S. Oliff, PhD