Abstract: We included 10 studies, with 623 participants (900 ears). Interventions included: oil-based treatments (triethanolamine polypeptide, almond oil, benzocaine, chlorobutanol), water-based treatments (docusate sodium, carbamide peroxide, phenazone, choline salicylate, urea peroxide, potassium carbonate), other active comparators (e.g. saline or water alone) and no treatment. Nine of the studies were more than 15 years old. The overall risk of bias across the 10 included studies was low or unclear. Primary outcome: proportion of patients (or ears) with complete clearance of ear wax Six studies (360 participants; 491 ears) contributed quantitative data and were included in our meta-analyses. Active treatment versus no treatment Only one study addressed this comparison. The proportion of ears with complete clearance of ear wax was higher in the active treatment group (22%) compared with the no treatment group (5%) after five days of treatment (risk ratio (RR) 4.09, 95% confidence interval (CI) 1.00 to 16.80); one study; 117 ears; NNTB = 8) (low-quality evidence). Active treatment versus water or saline We found no evidence of a difference in the proportion of patients (or ears) with complete clearance of ear wax when the active treatment group was compared to the water or saline group (RR 1.47, 95% CI 0.79 to 2.75; three studies; 213 participants; 257 ears) (low-quality evidence). Two studies applied drops for five days, but one study only applied the drops for 15 minutes. When we excluded this study in a sensitivity analysis it did not change the result. Water or saline versus no treatment This comparison was only addressed in the single study cited above (active versus no treatment) and there was no evidence of a difference in the proportion of ears with complete wax clearance when comparing water or saline with no treatment after five days of treatment (RR 4.00, 95% CI 0.91 to 17.62; one study; 76 ears) (low-quality evidence). Active treatment A versus active treatment B Several single studies evaluated 'head-to-head' comparisons between two active treatments. We found no evidence to show that one was superior to any other. Subgroup analysis of oil-based active treatments versus non-oil based active treatments We found no evidence of a difference in this outcome when oil-based treatments were compared with non-oil-based active treatments. Primary outcome: adverse effects: discomfort, irritation or pain Only seven studies planned to measure and did report this outcome. Only two (141 participants;176 ears) provided useable data. There was no evidence of a significant difference in the number of adverse effects between the types of ear drops in these two studies. We summarised the remaining five studies narratively. All events were mild and reported in fewer than 30 participants across the seven studies (low-quality evidence). Secondary outcomes Three studies reported 'other' adverse effects (how many studies planned to report these is unclear). The available information was limited and included occasional reports of dizziness, unpleasant smell, tinnitus and hearing loss. No significant differences between groups were reported. There were no emergencies or serious adverse effects reported in any of the 10 studies. There was very limited or no information available on our remaining secondary outcomes. Although a number of studies aimed to evaluate whether or not one type of cerumenolytic is more effective than another, there is no high-quality evidence to allow a firm conclusion to be drawn and the answer remains uncertain. A single study suggests that applying ear drops for five days may result in a greater likelihood of complete wax clearance than no treatment at all. However, we cannot conclude whether one type of active treatment is more effective than another and there was no evidence of a difference in efficacy between oil-based and water-based active treatments. There is no evidence to show that using saline or water alone is better or worse than commercially produced cerumenolytics. Equally, there is also no evidence to show that using saline or water alone is better than no treatment.

Plain-language summary: In March 2018 we searched for clinical trials where ear drops were used to help soften and remove build up of ear wax in patients' ears. We found and included 10 studies with a total of 623 participants. However, only six of these studies provided data with which we could analyse our primary outcome, the proportion of patients with complete ear wax clearance. These six studies included a total of 360 participants, both children and adults (of all ages), with partial or full blockage of the external ear canal with ear wax. The 10 included studies looked at either oil-based drops (triethanolamine polypeptide, almond oil, benzocaine, chlorobutanol), water-based drops (docusate sodium, carbamide peroxide, phenazone, choline salicylate, urea peroxide, potassium carbonate), saline (salty water) or water alone, or no treatment. Only one study compared using drops with an active ingredient to not using drops at all. The drops may help increase the proportion of ears cleared of wax from 1 in 20 (if you do nothing) to about 1 in 5 (if you use drops). We did not find any evidence that water-based or oil-based drops were any different to saline or water. However, we also did not find any evidence that water or saline were better than doing nothing. Adverse (side) effects were not common. Fewer than 30 patients reported any adverse events when using the drops and these were mild (such as slight irritation or pain, or unpleasant smell). No serious side effects were reported by any participant. We rated the quality of the evidence from studies using four levels: very low, low, moderate or high quality. High-quality evidence means that we are very confident in the results. Very low-quality evidence means that we are very uncertain about the results. For wax clearance, we rated the quality of the evidence as low. For adverse effects we rated the quality of the evidence as low. We have found that using ear drops when you have a partially or completely blocked ear canal may help to remove the ear wax in your ear. It is not clear whether one type of drop is any better than another, or whether drops containing active ingredients are any better than plain or salty water.