Table 3. Arms and method of assessing pruritus in the included studies (n = 8).

VAS: visual analog scale; WI-NRS: Worst Itching Intensity Numerical Rating Scale

Study	Omega-3 form/route/dose	Control	Pruritus assessment tool
Peck et al. [12,13]	Soft-gel capsules containing 1 g fatty acid ethyl ester (National Oceanic and Atmospheric Administration, Charleston Laboratory). Dose: six capsules/day for eight weeks	SA: soft-gel capsules containing 1 g fatty acid ethyl ester (National Oceanic and Atmospheric Administration, Charleston Laboratory). Dose: six capsules/day for eight weeks	Duo questionnaire
Begum et al. [31]	Soft-gel capsules containing 1 g fish oil fatty acid ethyl ester (National Oceanic and Atmospheric Administration, Charleston Laboratory). Dose: six capsules/day for 16 weeks	Soft-gel capsules containing 1 g fatty acid ethyl ester (National Oceanic and Atmospheric Administration, Charleston Laboratory). Dose: six capsules/day for 16 weeks	Duo questionnaire
Ghanei et al. [32]	Fish oil 1 g capsules (Zahravi, Tabriz, Iran) three capsules/day for 20 days. After a 14-day washout period, they were treated with a placebo for 20 days	Identical placebo capsules for 20 days. After a 14-day washout period, they were treated with omega-3 for 20 days	Duo questionnaire
Lahiji et al. [33]	Three 1 g omega-3 capsules (Zahravi, Tabriz, Iran) per day for one month. After a washout period of six weeks, patients were crossed over to the alternate treatment	Three 1 g placebo capsules (Zahravi, Tabriz, Iran) per day for 1 month. After a washout period of six weeks, patients were crossed over to the alternate treatment	VAS
Shayanpour et al. [34]	A single dose of 2 g omega-3 capsules daily before lunch for three weeks	A single dose of placebo capsules three daily before lunch for three weeks	5-D itch scale
Heydarbaki et al. [35]	1 g of omega-3 three times a day + 5 mg cetirizine three times a week for six weeks. After a washout period of one week, groups changed the treatments	5 mg of cetirizine three times a week for six weeks. After a washout period of one week, groups changed the treatments	VAS
Forouhari et al. [36]	Omega-3 1 g capsules (Zahravi, Tabriz, Iran) three times a day for four weeks. After a six-week washout period, a placebo is received for four weeks	Placebo capsules (Zahravi, Tabriz, Iran) three times a day for four weeks. After a six-week washout period, omega-3 is received for four weeks	VAS
Rafieipoor et al. [37]	Three 1 g capsules of omega-3 fatty acids/day (Zahravi Pharmaceutical Co, Tabriz, Iran) for two months	Three placebo capsules containing medium-chain triglyceride (Zahravi Pharmaceutical Co, Tabriz, Iran) for two months	WI-NRS