1. Reports of adverse events in individual studies.
| Study ID | Intervention | Reported side effect | Number of events in treatment group (N) | Number of events in control group (N) |
| 2nd NA IgAN 2004 | MMF versus placebo | Malignant melanoma, multiple intra‐abdominal injuries | 0+1 (13) | 1+0 (15) |
| Ballardie 2002 | Steroids + CPA versus no treatment | Pulmonary TB, overt diabetes, bone marrow toxicity, gastrointestinal toxicity | 1+1+1+1 (19) | 0+0+0+0 (19) |
| BRIGHT‐SC 2016 | Carboxylic acids (Blisibimod) versus placebo | Not reported | Not reported | Not reported |
| Cao 2008 | Steroids + leflunomide versus steroids | None reported | 0 (18) | 0 (18) |
| CAST‐IgA 2015 | Steroid + prednisolone + tonsillectomy + ARB versus steroid + prednisolone | Not reported | Not reported | Not reported |
| Chen 2002 | MMF versus prednisone | Diarrhoea, herpes zoster, nausea | % participants reported diarrhoea, herpes zoster, nausea (31) | Not reported |
| Cheung 2018 | Belimumab versus placebo | Not reported | Not reported | Not reported |
| Cruzado 2011 | Macrolide lactams (sirolimus) versus usual care | Fever, reversible hyperkalaemia, prostatic syndrome, unspecific acute gastritis, cholesterol increase, anaemia, oedema, mild facial rash | 0+1+1+1+2+1+2+2 (14) | 1+1+0+0+0+0+0+0 (9) |
| Frisch 2005 | MMF versus placebo | Gastrointestinal effects, deep vein thrombosis | 2+0 (17) | 2+1 (15) |
| Harmankaya 2002 | Steroids + AZA versus no treatment | Increased transaminase levels, minor cushingoid features, gastric pain | 1+2+1 (21) | 0 (22) |
| Hirai 2017 | Mizoribine versus usual care | Hepatotoxicity, low‐grade fever, malignant lymphoma | 1+1+1 (21) | 0+0+0 (21) |
| Horita 2007 | Steroids + RAS inhibitors versus steroids | Hypotension | 2 (20) | 0 (20) |
| Hou 2017 | MMF versus prednisone | Pneumonia, acute kidney injuries, ophthalmos‐neuritis, osteonecrosis of the femoral head, ESKD, gastric perforation, newly diagnosed diabetes, impaired glucose tolerance, infections, hepatic dysfunction, gastrointestinal symptoms, cushing syndrome, acne, cramps, insomnia, alopecia, tremors | 3+1+1+0+0+0+1+12+27+9+7+16+2+5+12+5+5 (87) | 4+0+0+1+1+1+12+15+20+14+10+42+5+11+17+11+7 (88) |
| Julian 1993 | Steroids versus no treatment | Overt diabetes, insomnia, acne | 2+2+3 (18) | 1 (17) |
| Kanno 2003 | Steroids versus warfarin | None reported | 0 (6) | 0 (4) |
| Katafuchi 2003 | Steroids + dipyridamole versus dipyridamole (in an abstract (Katafuchi 1997) that reported steroids versus antiplatelet agent in 80 participants, no adverse events were reported) |
Palpitations/insomnia | 3 (43) | 1 (47) |
| Kawamura 2014 | Methylprednisolone + tonsillectomy versus steroid | None reported | 0 (33) | 0 (39) |
| Lee 2003 | Steroids + ARB versus ARB | Not reported | Not reported | Not reported |
| Kim 2013b | Tacrolimus versus placebo | Cardiovascular, gastrointestinal, genitourinary, hematologic, musculoskeletal, neurologic, respiratory, dermatologic | 2+21+4+1+3+12+4+2 (20) | 1+4+0+0+3+1+5+1 (20) |
| Kobayashi 1996 | Steroids versus no treatment | None reported | 0 (20) | 0 (26) |
| Koike 2008 | Prednisolone + dipyridamole versus dipyridamole | None reported | 0 (24) | 0 (24) |
| Koitabashi 1996 | Chinese medicine (Saireito) versus no treatment versus prednisolone + AZA + anticoagulants + dipyridamole versus anticoagulants + dipyridamole | Not reported | Not reported | Not reported |
| Lafayette 2017 | Rituximab versus usual care | Cough, fever, flu, gastrointestinal symptoms, embolism, infections, rush, nasal congestion, eye problems, wart left 5th digit, right flank tenderness, headache, haemorrhage, pruritus, confusion, fatigue, muscle problems, back pain, dyspnoea, heartburn and cardiac problems, anorexia, sore throat, flushing, hypertension, photosensitivity, vaginal bleeding, left hand numbness | Not reported (17) | Not reported (17) |
| Lai 1986 | Steroids versus no treatment | Gastritis, hypertension | 1+3 (17) | 0+0 (17) |
| Lai 1987 | CSA versus placebo | Dyspepsia, headache, hypertension, hirsutism | 6+7+1+3+7 (12) | 0+0+0+0+1 (12) |
| Liu 2010a | Prednisone + leflunomide versus prednisone + MMF | Not reported | Not reported | Not reported |
| Liu 2014 | Methylprednisolone + CSA versus methylprednisolone | Severe pneumonia, recurrent urinary tract infection, elevated blood sugar, eyesight degradation | 3+2+2+5 (23) | 1+3+2+9 (25) |
| Locatelli 1999 | Steroids + AZA versus steroids | Hepatotoxicity, leukopenia, GI symptoms, bacterial Infections, viral Infections, Pneumocystis carinii infection, type 2 diabetes, hypertension | 5+3+3+3+1+1+1+0 (101) | 0+0+0+2+1+0+2+1 (106) |
| Lou 2006 | Leflunomide versus RAS inhibitors | Serum transaminases, mild alopecia, severe diarrhoea, cough | 2+1+1+0 (24) | 0+0+0+2 (22) |
| Lv 2009 | Steroids + RAS inhibitors versus RAS inhibitors | Cough, hyperkalaemia, palpitation, arthralgia | 2+0+1+1 (33) | 1+0+0+0 (30) |
| Maes 2004 | MMF versus placebo | Reactivation of pulmonary TB, gastrointestinal complaints, leukopenia, rectal carcinoma | 1+2+1+0 (21) | 0+0+0+1 (19) |
| Manno 2001 | Steroids + RAS inhibitors versus RAS inhibitors | Striae, glucidic intolerance, cough | 3+1+0 (48) | 0+0+2 (49) |
| Masutani 2016 | Prednisolone followed by mizoribine versus prednisolone | Pneumonia, herpes zoster, severe drug allergy | 2+0+0 (20) | 0+1+1 (20) |
| Min 2017 | Leflunomide + prednisone versus full dose prednisone | Hepatotoxicity, upper respiratory infection, pulmonary infection, diarrhoea, herpes‐zoster virus infection, pruritus, insomnia, alopecia, abnormal glucose metabolism | 3+4+2+1+0+1+0+1+0 (40) | 2+4+1+0+2+0+2+0+2 (45) |
| NA IgAN 1995 | Steroids versus placebo | Heartburn, increased appetite, weight gain | 15+24+22 (33) | 5+10+13 (31) |
| NEFIGAN 2017 | Low dose TRF‐budesonide versus high dose TRF‐budesonide versus placebo | Nasopharyngitis, acne, joint swelling, cushingoid, insomnia, diarrhoea, dyspepsia, headache, alopecia, back pain, mood swings, oedema peripheral, blood creatine phosphokinase increased, hirsutism, hypertension, muscle spasms, abdominal pain, nausea, upper respiratory tract infection | Treatment group 1 8+8+8+5+6+1+2+3+4+6+3+2+3+3+3+5+4+4+2 (51) Treatment group 2 10+9+9+8+8+5+7+6+4+3+5+6+3+5+5+2+3+3+3 (49) |
10+3+2+3+2+7+4+3+2+1+2+2+3+1+1+2+1+1+3 (50) |
| Ni 2005 | Steroids + leflunomide versus steroids | Elevated liver enzyme, infection, diarrhoea, nausea, rash, insomnia, blood glucose increase | 4+8+2+1+1+0+0 (51) | 4+10+0+0+1+1+1 (51) |
| Nuzzi 2009 | Steroids versus no treatment | None reported | 0 (15) | 0 (12) |
| Pozzi 1999 | Steroids versus no treatment | None reported | 0 (43) | 0 (43) |
| Segarra 2006 | Immunoglobulin + steroids versus steroids | Cutaneous rush, DM | 1+0 (19) | 0+1 (17) |
| Shen 2013 | Corticosteroid + CPA versus corticosteroid + tacrolimus versus corticosteroid | Not reported | Not reported | Not reported |
| Shi 2012a | Steroids + leflunomide versus steroids | Adverse events were assessed but not clearly reported | Not reported | Not reported |
| Shima 2018 | Prednisolone + mizoribine + warfarin + dipyridamole versus prednisolone + mizoribine | Obesity, hyperuricaemia, hypertension, headache, steroid‐induced gastric ulcer, glaucoma, steroid acne, stretch marks, bleeding, decreased bone mineral density, cataract, elevation of serum bilirubin, psychosis | 6+2+1+6+2+2+2+1+2+0+0+0+0 | 7+5+6+0+3+2+2+1+0+1+1+1+1 |
| Shoji 2000 | Steroids versus dipyridamole | Headache | 0 (11) | 1 (8) |
| Stangou 2011 | AZA + methylprednisolone versus methylprednisolone | Not reported | Not reported | Not reported |
| STOP‐IgAN 2008 | Methylprednisolone versus no treatment | Diverticulitis or appendicitis, pneumonia or respiratory tract infection, viral exanthema, knee empyema, death, malignant neoplasm, impaired glucose tolerance or DM, gastrointestinal bleeding, fracture, osteonecrosis, weight gain | 3+3+1+1+1+2+9+0+1+0+14 (82) | 1+1+1+0+1+0+1+0+0+0+5 (80) |
| Takeda 1999 | Steroids + antiplatelet agent versus antiplatelet agent | None reported | 0 (13) | 0 (12) |
| Tang 2005 | MMF + RAS inhibitors versus RAS inhibitors | Fall in haemoglobin level, diarrhoea, upper gastrointestinal upset, infective episodes | 3+1+1+3 (20) | None reported (20) |
| TESTING 2017 | Methylprednisolone versus placebo | Respiratory infection, pneumocystis pneumonia, cryptococcal meningitis, nocardia infection of skin and knee joint, perianal abscess, urinary tract infection, fever, duodenal ulcer, gastrointestinal bleeding, gastric perforation, vascular necrosis, osteochondroma, pulmonary embolism, deep vein thrombosis, hepatotoxicity, haemoptysis, acute right upper quadrant pain, arthralgia, symptomatic incarcerated paraumbilical hernia, uremia, soft tissue injury, new‐onset DM, vascular necrosis, fracture | 4+3+1+1+1+1+1+1+2+1+2+1+1+2+1+1+1+1+0+0+ 1+2+1+1 (136) |
0+0+0+0+0+0+0+0+0+1+0+0+0+0+0+0+0+0+1+2+ 0+3+0+0 (126) |
| Walker 1990a | CPA + dipyridamole + warfarin versus no treatment | Gonadal toxicity, headache | 2+1 (25) | 0+0 (27) |
| Welch 1992 | Steroids versus placebo | None reported | 0 (20) | 0 (20) |
| Woo 1987 | CPA + dipyridamole + warfarin versus no treatment | Gum bleeding | 2 (27) | 0 (21) |
| Wu 2016 | Telmisartan + clopidogrel placebo + leflunomide placebo versus telmisartan + clopidogrel + leflunomide placebo versus telmisartan + clopidogrel placebo + leflunomide versus telmisartan + clopidogrel + leflunomide | Death, abnormal liver function, hypotension, hyperkalaemia, neutropenia, rash, skin purpura, upper gastrointestinal bleeding, herpes zoster, urinary tract infection, upper respiratory tract infection | Treatment group 1 0+0+0+1+1+0+0+0+1+0+1 (100) Treatment group 2 0+3+1+2+0+0+0+0+0+1+0 (100) Treatment group 3 0+1+2+1+0+0+0+0+0+0+0 (100) |
0+3+0+0+2+2+1+1+0+0+0 (99) |
| Xie 2011 | Mizoribine versus losartan versus combination group | Serious adverse events, hyperuricaemia, upper respiratory tract infection, herpes zoster, leukopenia, elevation of transaminases, vertigo, alopecia | Treatment group 1 0+3+1+0+1+1+0+0 (35) Treatment group 2 0+1+3+0+1+1+1+0 (30) |
0+3+2+1+0+0+1+1 (34) |
| Yoshikawa 1999 | Steroids + AZA + dipyridamole versus dipyridamole | Alopecia, anaemia, leukopenia, cataract, ulcer, depression | 1+0+3+1+1+1 (40) | 0+1+0+0+0+0 (38) |
| Yoshikawa 2006 | Steroids + dipyridamole + AZA + warfarin versus steroids | Hypertension, glucosuria, aseptic necrosis of femur, glaucoma, cataract, headache, leukopenia, bleeding, anaemia, elevated transaminase concentration | 0+0+1+2+0+3+3+1+1+2 (40) | 5+3+1+2+2+0+0+0+0+1 (40) |
| Zhang 2004 | Leflunomide versus steroids | Elevate liver enzyme, nausea, lose hair, leukopenia | 3+1+1+1 (27) | None reported (22) |
ARB ‐ angiotensin receptor blocker; AZA ‐ azathioprine; CPA ‐ cyclophosphamide; CSA ‐ cyclosporin A; DM ‐ diabetes mellitus; MMF ‐ mycophenolate mofetil; RAS ‐ renin‐angiotensin system; TB ‐ tuberculosis; TRF‐budesonide ‐ targeted‐release formulation of budesonide