After surgery: Can ginger help prevent nausea and vomiting after an operation?

Low doses of ginger supplements before surgery cannot prevent nausea and vomiting afterwards. Doses of at least 1g might be able to help some people, but more research is needed to be sure. Ginger is not likely to cause major adverse effects.

Nausea and vomiting are common after surgery, and this can sometimes make it more difficult to treat pain. The rate of what is called post-operative nausea and vomiting (PONV) depends on the type of surgery, anaesthetic and other factors. Nausea or vomiting can also be adverse effects of opioids (opium-based drugs). Opioids like morphine are used to relieve pain after surgery. One estimate is that an average of more than 30 percent of people are affected by nausea and vomiting after surgery, although, for about half of them, it does not continue for long. For some types of long operations, including gynaecological surgery, the rate of nausea and vomiting can be even higher.

Some people are at a higher risk of feeling nauseous, for example people who are very overweight. When it is particularly severe, nausea and vomiting can complicate and delay recovery after surgery, or stop people from using enough pain medication. Drugs that can prevent or reduce nausea or vomiting are called "antiemetics". Although several types of these drugs are used before and after surgery, there is no "ideal" drug that can prevent nausea after an operation. This means that different alternatives are often tried, including complementary therapies like acupuncture or herbal medicines.

One option is to use a ginger supplement (called "zingiberis officinale" in Latin). Ginger is used for nausea and vomiting in traditional Asian medicine. For example, there is some evidence that it might be able to reduce the effects of morning sickness during pregnancy. It is not known exactly why ginger might be able to reduce nausea and vomiting. Ginger supplements do not appear to cause major adverse effects, although they can cause heartburn (indigestion).

The nausea and vomiting after surgery can be more severe than other types of nausea. This means that even if ginger works for one of these other kinds of nausea, like morning sickness, we cannot automatically assume that ginger would also prevent nausea after an operation. To determine whether research has proven ginger to be effective for this problem, researchers from Thailand looked for trials that used at least 1g of ginger before surgery to try to prevent nausea and vomiting. They found five trials that looked at this, including just over 350 patients.

Ginger was able to prevent at least some nausea and vomiting, but the researchers point out that most of the people in these trials were from Asia, and they had an average body weight of 50kg. This is less than the average weight of people from European and American countries. That could mean that a dose of 1g of ginger is not enough to be effective in heavier people. The higher doses used in the trials were 2g or more. Researchers in Germany looked at trials where the dose was lower than 1g too, and concluded that these ginger supplements cannot prevent post-operative nausea and vomiting. They also doubt that higher doses can really help. This means that there are still many open questions about ginger as a preventive treatment for nausea after surgery.

We will update this information when more research becomes available. In the meantime, if people do want to take ginger as a way to try to prevent postoperative nausea and vomiting, they should not expect a benefit from a dose of less than 1g.

© IQWiG (Institute for Quality and Efficiency in Health Care)