Saffron side effects: what the trials actually recorded

At the amounts used in the research, around 28 to 30 milligrams a day of a standardised saffron extract, the trials have recorded few side effects. The ones reported most often are nausea, dry mouth, poor appetite and headache, and the reviews that pool this research report no serious reactions.

That is the short answer. Here is what sits behind it, trial by trial, and the one thing that genuinely changes the picture: the amount.

What the trials of one extract recorded

The most useful evidence comes from trials run on a single standardised extract, because every one of them tested the same material at the same kind of amount. Eleven placebo-controlled trials have used it. Several report side effects in enough detail to be worth reading.

• 120 adults, 28 days. Participants took 14 mg, 28 mg or a placebo an hour before bed. Reported side effects: nine in the placebo group, five at 14 mg and nine at 28 mg. In other words, the saffron groups reported side effects no more often than the placebo group. (Lopresti, Smith and Drummond, Sleep Medicine, 2021, PMID 34438361.)
• 55 adults, 28 days. 14 mg twice a day or placebo. No adverse events were reported. Asked whether they were happy taking the tablets, 4 per cent of the saffron group said they were not, against 15 per cent of the placebo group. (Lopresti et al., Journal of Clinical Sleep Medicine, 2020, PMID 32056539.)
• 80 young people aged 12 to 16, eight weeks. 14 mg twice a day or placebo. The authors describe the extract as well tolerated. (Lopresti et al., Journal of Affective Disorders, 2018, PMID 29510352.)
• 52 adults, four weeks. Three adverse events were recorded across the trial, one of them influenza, and none was attributed to the saffron. (Takeda et al., Japanese Pharmacology and Therapeutics, 2020.)
• 202 adults, twelve weeks. The largest trial of the extract. Of the people who finished it, 95 per cent took more than 80 per cent of their tablets across the full three months, which is about as good a sign as a trial can give that people were comfortable taking something every day. (Journal of Nutrition, 2025, PMID 40414301.)

What the wider research says

Step back from one extract to saffron research as a whole and the picture holds.

In 2021 a team pulled together 19 separate meta-analyses of saffron published between 2013 and 2021, an umbrella review of the whole field. The common side effects they found reported were nausea, dry mouth, poor appetite and headache, and no serious adverse reactions were reported. (Lu et al., Phytomedicine, 2021, PMID 34419735.)

A toxicology review from Mashhad University of Medical Sciences went through the acute, short-term and long-term safety studies in animals and people. Its summary: at the amounts used in research and practice, saffron showed no significant toxicity in either clinical or experimental studies. (Bostan, Mehri and Hosseinzadeh, Iranian Journal of Basic Medical Sciences, 2017, PMID 28293386.)

The most recent look is a systematic review published in October 2026. It searched the literature up to 31 August 2026 and included 19 saffron studies, reporting its findings for standardised extracts at 15 to 30 mg a day. It concluded that saffron showed a favourable safety profile. The same review also covered ashwagandha, another plant often suggested for stress, and the one caution it raised was about ashwagandha: it advised liver enzyme monitoring during prolonged use. It raised no equivalent caution for saffron. (Alyami, Journal of Visualized Experiments, 2026, PMID 42858054.)

Blood tests at the trial amount

Questionnaires about side effects tell you what people noticed. Blood tests tell you what they might not have.

One twelve-week trial was designed specifically to look at safety. Sixty-six adult men with schizophrenia, already under psychiatric care, were given 15 mg of saffron extract twice a day, 15 mg of crocin (saffron's main colour compound) twice a day, or a placebo, alongside their usual care. That is almost exactly the daily amount the extract trials above used, and it ran for three months.

Sixty-one completed it. None reported a serious side effect. The researchers checked blood counts and markers of thyroid, liver and kidney function and inflammation. One measure, white blood cell count, rose in the saffron group but stayed within the normal range and was judged of no clinical significance. The other blood counts and the thyroid, liver, kidney and inflammation markers showed no statistically significant difference between the groups. (Mousavi et al., Avicenna Journal of Phytomedicine, 2015, PMID 26468460.)

Where the amount starts to matter

Saffron is a food, and like most foods the amount is what decides how it behaves. The trials above sit at around 28 to 30 mg a day. It is worth knowing what happens well above that.

In a one-week study, 30 healthy adults took placebo, 200 mg or 400 mg a day of saffron stigma tablets. That is the whole dried spice rather than a standardised extract, at many times the weight of the amounts used in the mood and sleep trials.

Nobody showed gross changes on examination. At 400 mg, standing blood pressure fell. Some blood and biochemical measures shifted slightly, and the authors noted these stayed within normal ranges and were not clinically important. (Modaghegh et al., Phytomedicine, 2008, PMID 18693099.)

The practical point cuts both ways. The amount in the research is small and has a long tolerability record. Much larger amounts start to show measurable effects on the body, which is exactly why a product should state its saffron amount plainly, and why that amount should match what was studied rather than exceed it.

Children and teenagers

Saffron has been part of family cooking across Persian, Indian, Spanish, Moroccan and Italian kitchens for thousands of years, and children in those households eat it as a matter of course.

In the research, the youngest participants in any placebo-controlled trial of the standardised extract were 12. That trial, in 12 to 16 year olds over eight weeks, is the one its authors describe as well tolerated. There is no placebo-controlled trial of the extract in younger children, and it would be wrong to suggest there is.

When to check with your GP

The sensible checks are the ordinary ones for any new food ingredient taken daily.

• If your child takes regular medication or has an ongoing medical condition, have a conversation with your GP or pharmacist first.
• If you are pregnant, that is its own question, separate from anything in this article, and one for your doctor.
• If anything unexpected shows up after starting something new, stop and ask.

What to take from it

At around 28 to 30 mg a day of a standardised extract, saffron trials have recorded few side effects, most often nausea, dry mouth, poor appetite and headache, and no serious reactions. In the trial that counted them side by side, the saffron groups reported side effects no more often than placebo, and a three-month trial that ran blood panels at the same daily amount found nothing of clinical concern.

The figure that matters is the amount. Look for it on the label, and check that it matches what the research used.

Studies conducted on individual ingredients, not on any finished product. Individual results may vary. This article reports published research. It is not medical advice and does not replace a conversation with your GP.