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5-HTP, or 5-hydroxytryptophan, is used by your body to produce brain chemicals like serotonin. Serotonin helps regulate your mood, appetite and energy level. 5-HTP helps maintain your serotonin levels, which can alleviate depression, kick-start weight loss and increase your energy. While 5-HTP can be beneficial, it does have side effects that can include mild gastrointestinal problems.


Your digestive system can be sensitive to serotonin, and 5-HTP can lead to some mild nausea. The higher the dose, the more likely this is to happen. Higher doses are generally given to patients who are using 5-HTP to help with weight loss or fight obesity. Standard doses of 50mg to 100mg don't tend to bring on nausea.


If your serotonin level becomes too high, you can develop serotonin syndrome. If this happens, you could experience side effects, one of which is diarrhea. The risks of serotonin syndrome increase when you take 5-HTP in combination with MAOIs, or monamine oxidase Inhibitors, as MAOIs prevent serotonin from being chemically broken down. Consult your doctor before beginning or ending any drug program.

Empty Stomach

If your reason for starting 5-HTP is appetite regulation, you should take it about 20-30 minutes before eating so that it will enter your brain and begin converting to serotonin faster. If you have other reasons for taking 5-HTP, you should be able to take it three times a day in small doses without nausea. You won't have to take it before meals if the purpose for taking it is not to promote weight loss or combat obesity.

After Meals

If you tend to eat more during the night hours than in the morning or during the day, it may be beneficial to take a 100mg dose of 5-HTP immediately after your last meal. If nausea follows, it should be temporary and subside after a few days. Sipping a ginger ale can be beneficial if nausea occurs after a meal. Avoid caffeinated drinks, as these can keep you awake as well as counteract the effects of 5-HTP.

Gastrointestinal Side Effects

Other side effects of 5-HTP that occur in the stomach are loss of appetite, diarrhea, cramps, vomiting and gas. Most of these symptoms occur when you take more than 100 mg of 5-HTP. Taking 5-HTP with meals can reduce the gastrointestinal side effects.