Can you still take a blood test if you have eaten?

Blood tests & eating: Only a few blood tests require that you be fasting--most particularly tests for sugar (glucose) and a lipid panel (because the triglycerides go very high after eating. Most other tests do not require a fasting state--including electrolytes, thyroid tests, liver tests, total cholesterol & HDL cholesterol, kidney function, and blood counts.

Better not to.: Although some values are not affected too much by eating, it is better not to eat before a blood test because other values, like blood sugar and triglycerides, might be greatly affected. They might even have to be redone, since values, notably blood glucose are often measured on the premise that you are fasting.

Depends on the test: Some tests are best done in fasting state, e.G, lipids/cholesterol, and glucose. For most tests it is not necessary to be fasting.