Fermoso 1992.

Study characteristics
Methods	Study design: randomised, double‐blind, placebo‐controlled Method of randomisation: not stated Exclusions post randomisation: none Losses to follow‐up: 6/34 (18%)
Participants	Country: Spain Setting: hospital Number: 34 patients Age: mean 53 ± 18 (range 21 to 86) years Gender: 20 M:14 F Inclusion criteria: CVI (varicose veins and/or disturbances of venous circulation by Doppler) Exclusion criteria: not stated
Interventions	Treatment: hidrosmine 600 mg per day Control: placebo Duration: 28 days Follow‐up: 28 days
Outcomes	Primary Symptoms ‐ local tension, pain, paraesthesia, heaviness, pruritus, cramps measured by a semiquantitative scale (0 to 4) Signs ‐ oedema, varicose ulcers, trophic disorders and abnormal skin colour as measured by presence or absence Venous circulation using Doppler Secondary Side effects
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Quote: "The 34 patients chosen were randomly assigned to two treatment groups" Comment: no methods of randomisation described
Allocation concealment (selection bias)	Unclear risk	Comment: no methods of allocation concealment described
Blinding (patients)	Low risk	Quote: "And the other group received placebo capsules indistinguishable from the hidrosmin capsules, according to the double‐blind technique" Comment: Identical placebo ensures double‐blinding
Blinding (study researchers)	Low risk	Quote: "And the other group received placebo capsules indistinguishable from the hidrosmin capsules, according to the double‐blind technique" Comment: Identical placebo ensures double‐blinding
Blinding (outcome assessment)	Low risk	Quote: "And the other group received placebo capsules indistinguishable from the hidrosmin capsules, according to the double‐blind technique" Comment: Identical placebo ensures double‐blinding
Incomplete outcome data	Low risk	Comment: number of participants in each group described. In addition, number of participants who prematurely withdrew from the study (6/34; 18%) described
Selective reporting	Low risk	Comment: no published protocol identified, and no differences between outcomes reported in the methods section and those reported in the results section
Other bias	Low risk	Comment: none detected