This study would assess the clinical efficacy of add-on topical timolol 0.5% gel to betamethasone valerate 0.1% for the treatment of EGFR-TKI induced paronychia. Eligible patients, who develop paronychia (affecting fingernails, toenails or both), will be included in this study. They will be randomized in 1:1 ratio using computer-generated randomization list to receive either combination of topical timolol 0.5% gel and betamethasone valerate 0.1% lotion application twice daily or betamethasone valerate 0.1% lotion application twice daily. Patients in timolol combination treatment group will receive topical timolol 0.5% gel twice daily with occlusion (i.e. covered with adhesive badge) and betamethasone valerate 0.1% lotion twice daily with occlsuion for 1 month. Patients in routine arm would receive the management according to routine clinical practice, including prescription of betamethasone valerate 0.1% lotion twice daily for 1 month with occlusion. For patients who do not have paronychia completely resolved after 4 weeks, the treatment assigned will be continued for another 4 to 8 weeks , up to 12 weeks to see the effect.

The aim of this study ist o assess the clinical efficacy of add-on topical timolol 0.5% gel to betamethasone valerate 0.1% for the treatment of EGFR-TKI induced paronychia.

Inclusion Criteria:

1. Aged 18 years or above, either males or females.
2. Received EGFR-TKI, namely gefitinib, erlotinib, afatinib, osimertinib, amivantamab, dacomitinib and mobocertinib.
3. Paronychia (fingernails, toenails, or both) as an adverse event from EGFR-TKI use.
4. Written informed consent obtained from patient.

Exclusion Criteria:

1. Age below18.
2. Patients who are allergic to, or contraindicated to topical timolol use.
3. Pregnant women or nursing mother.
4. Non-consenting patients.

This is an open-label trial, and no one will be masked