Sulbutiamine

What sulbutiamine is

Sulbutiamine is a disulfide made of two thiamine molecules, that is, two building blocks of vitamin B1, which additionally carry isobutyryl groups. This makes it fat-soluble, unlike the water-soluble thiamine in food. In the body, it is converted back into thiamine; the French summary of product characteristics explicitly lists thiamine as a metabolite. According to the same document, sulbutiamine is absorbed rapidly, reaches its highest blood concentration after one to two hours and has a half-life of about five hours.

It is related to benfotiamine, another fat-soluble vitamin B1 precursor. Benfotiamine is used mainly in nerve damage due to diabetes, sulbutiamine on the other hand because of its effect on drive and exhaustion.

How it works

The idea: a fat-soluble molecule crosses the blood-brain barrier more easily than thiamine and raises the levels of thiamine and its phosphate compounds in the brain. That is how study authors summarize it on the basis of animal data (Sevim 2017), supplemented by described effects on cholinergic and dopaminergic signaling pathways (Ahmed Mahmoud 2026). The French summary of product characteristics relies on controlled studies with psychometric tests and describes an effect mainly on psychological and physical inhibition of drive.

Little of this has been measured in humans. Which levels arise in the human brain and which signaling pathway carries the observed effects has not been studied directly.

What the studies show

Tiev 1999 – post-infectious exhaustion, placebo-controlled

326 patients from general practices with chronic exhaustion after an infection received, double-blind, 400 mg or 600 mg of sulbutiamine daily or placebo, each for 28 days; 315 completed the study. Measured with a validated multidimensional fatigue questionnaire, there was no significant difference between the groups overall. On day 7, women under 600 mg were less exhausted (p < 0.01); by day 28, none of this was detectable any more. The authors themselves leave open whether this finding is real.

Lôo 2000 – add-on in depression

Randomized, double-blind, placebo-controlled study over eight weeks in inpatients with a major depressive episode, all on clomipramine; sulbutiamine was tested at 600 mg per day. The depression itself improved equally in both groups. On the scales for psycho-behavioral inhibition, that is, drive and everyday functioning, patients under sulbutiamine were significantly less impaired after four weeks. Safety data showed no differences, including no mania.

Kiew 2002 – diabetic polyneuropathy

30 patients with type 2 diabetes and nerve damage were openly assigned to sulbutiamine or no treatment for six weeks. Nerve conduction velocity and muscle action potentials in arm and leg nerves improved significantly under sulbutiamine compared with the control group (each p < 0.001), symptoms in the group comparison did not. Without placebo and blinding.

Sevim 2017 – fatigue in multiple sclerosis

26 patients with MS fatigue took 400 mg daily for two months; there was no control group. The fatigue score fell on average from 77 to 60.5 (p < 0.01); improvement was seen mainly in patients on a disease-modifying therapy (13 of 23 versus 0 of 5). No serious side effects occurred.

Ahmed Mahmoud 2026 – nocturnal enuresis in children

450 children aged 6 to 18 were assigned to imipramine, sulbutiamine or both and followed for six months. Complete response occurred in 52.7 percent under sulbutiamine, 60 percent under the combination and 37.3 percent under imipramine (p = 0.003); relapses were less frequent under sulbutiamine (28.7 versus 43.6 percent). Side effects occurred less often under sulbutiamine. The comparison was with a medicine, not with placebo.

Shah 2003 – exhaustion in infections, observational study

1,772 patients with an infectious disease and a feeling of weakness received 15 days of sulbutiamine in addition to treatment of the infection, without a control group and organized close to the manufacturer. In 51.7 percent, the symptoms disappeared completely; side effects were reported in 0.6 percent. Because most infections clear up on their own, this says little about the effect of the drug.

What users report

In a 2021 survey at the University of Lille with 4,431 responding students, 0.6 percent stated that they had taken sulbutiamine. 85.7 percent of these users named better concentration as the reason, 46.4 percent more alertness; 7.1 percent reported a feeling of dependence (Carton 2023). That is a small group and self-reporting, not proof of efficacy.

Where the data stop

For the reason sulbutiamine is mostly bought today, more focus, motivation and mental energy in healthy people, there is no controlled study. The data come from disease conditions and are mostly older, small and short: 4 to 8 weeks in the placebo-controlled studies. The largest placebo-controlled study missed its goal.

Several studies ran without placebo or blinding; particularly in exhaustion and fatigue this is a problem, because these complaints respond strongly to expectation and often clear up on their own. Long-term data over months or years do not exist for adults, nor are there studies on whether tolerance develops.

Status, approval and legal

In France, Arcalion 200 mg from Servier is an approved medicine, without prescription requirement and without reimbursement. It is approved for the treatment of certain states of physical or psychological inhibition with reduced activity and lack of drive; treatment duration is limited to four weeks, and it is not intended for children and adolescents.

In Germany, sulbutiamine is not an approved medicine. It is listed neither in the German Prescription Drug Ordinance nor in the Narcotics Act. It may not be sold as a food supplement: the EU permits only four compounds for vitamin B1 in food supplements, thiamine hydrochloride, thiamine mononitrate, thiamine monophosphate chloride and thiamine pyrophosphate chloride; sulbutiamine is not one of them.

Safety

The French summary of product characteristics lists as occasional side effects agitation, headache, tremor, nausea, vomiting, skin rash and malaise, and with unknown frequency stomach pain and diarrhea. Overdose leads to agitation with euphoria and tremor of the hands and feet, transient according to the summary of product characteristics. There are no data on fertility; it should not be used during pregnancy and breastfeeding. No specific interaction studies have been conducted.

A case report describes a patient with bipolar disorder who took ever larger amounts of sulbutiamine and whose treatment suffered as a result (Douzenis 2006). Together with the feeling of dependence that some student users reported, this is an indication not to treat sulbutiamine as a harmless vitamin. Anyone with a mental illness should discuss taking it with a physician.

Sources

• Tiev KP et al., Rev Med Interne 1999 – 400 or 600 mg versus placebo in post-infectious exhaustion, 326 patients (PMID 10573727)
• Lôo H et al., Encephale 2000 – add-on to clomipramine in major depressive episode (PMID 10858919)
• Kiew KK et al., Malays J Med Sci 2002 – open randomized study in diabetic polyneuropathy (PMID 22969314)
• Shah SN, J Assoc Physicians India 2003 – observational study in 1,772 patients with infection-related asthenia (PMID 14710977)
• Sevim S et al., Mult Scler Relat Disord 2017 – fatigue in multiple sclerosis, 26 patients (PMID 28755683)
• Ahmed Mahmoud T et al., J Pediatr Urol 2026 – RCT versus imipramine in nocturnal enuresis, 450 children (PMID 42107294)
• Douzenis A et al., World J Biol Psychiatry 2006 – case report of misuse in bipolar disorder (PMID 16861144)
• Carton L et al., Dialogues Clin Neurosci 2023 – PETRA survey among students in Lille (PMID 37837439)
• Base de Données Publique des Médicaments – Arcalion 200 mg, summary of product characteristics (RCP, ANSM, as of 16.06.2021)
• Regulation (EC) No 1170/2009 – permitted vitamin and mineral substances in food supplements (Annex II Directive 2002/46/EC)