A medicine cabinet rarely dies all at once. The door starts to sag, a dark line creeps along the edge of the mirror, the light flickers once too often, and one day you decide the whole unit has to go. Sometimes that is the right call. Just as often, the cabinet is fine and one cheap component is not, or the cabinet is failing because of a bathroom problem that will kill its replacement just as quickly. Whether you are in a Vancouver condo, a Prairie bungalow or a century home in Halifax, the smart sequence is the same: diagnose first, spend second.
Start with the symptom, not the solution
Medicine cabinet failures follow a fairly predictable order of likelihood. Hardware wears out first, mirror surfaces and finishes go second, electrics third, and the box itself last. The cheap fixes cluster at the top of that list, the honest replacement triggers at the bottom. Here is the quick reference.
| Symptom | Most likely culprit | Try first | Replace when |
|---|---|---|---|
| Sagging or rubbing door | Loose or worn hinges | Tighten and adjust the hinge screws | Screw holes are stripped in a swollen carcass |
| Black spots or edges on the mirror | Moisture attacking the silver backing | Fix ventilation and cleaning habits | Desilvering has spread into the viewing area |
| Rust or swelling inside the box | Chronic humidity plus budget materials | Sand and seal small spots, improve airflow | The box is rusted through or delaminating |
| Lights or demister dead | Switch, GFCI or LED driver, not the cabinet | Check the circuit and reset the GFCI | Integrated parts are obsolete and unavailable |
| Shelves slipping or cracked | Worn shelf clips | Order replacement clips or shelves | Almost never on its own |
The cheap fixes, in the order to try them
Sagging, rubbing or misaligned doors. This is the single most common complaint, and it is almost always hinges. Most cabinets from the last couple of decades use adjustable European-style hinges with small screws controlling height, depth and side-to-side position. Snug the mounting screws, then turn the adjustment screws a quarter turn at a time until the door hangs square. Older pivot hinges wear rather than loosen, and generic replacements are widely available.
Weak or sticky catches. A door that will not stay shut usually has a tired magnetic catch or a roller catch full of grime. Clean it, bend the strike plate back into position, or swap in an inexpensive universal replacement.
Mirror desilvering. Those black speckles and creeping dark edges mean moisture has reached the reflective backing. A frequent accelerant is glass cleaner sprayed directly onto the mirror, where it pools along the bottom edge and wicks behind the glass. There is no repair for desilvering, but it matters how you read it: light edge spotting on an old cabinet is cosmetic and liveable, and some manufacturers, including higher-end brands like Sidler and Duravit, can supply replacement doors or mirror panels for current models. Treat desilvering above all as a ventilation warning, because a new mirror in the same conditions will follow the same path.
Dead lighting or demister pads. On lighted cabinets, work outward from the wall. Confirm the wall switch works, then check for a tripped breaker or GFCI, which in many Canadian bathrooms protects everything on the circuit. If power is reaching the cabinet, the usual failure is the LED driver rather than the light strip itself, and drivers on better cabinets are replaceable service parts. Only condemn the whole unit once the manufacturer confirms parts are no longer available.
Rust spots and tired shelves. Minor surface rust inside a steel box can be sanded and sealed with an appropriate paint. Cracked glass shelves and worn shelf clips are standard replacement parts. Neither justifies a new cabinet on its own, though it is telling that better cabinets use aluminum or stainless carcasses precisely to shrug off bathroom humidity.
The misdiagnosis trap: it is usually the bathroom, not the cabinet
Most cabinet-killing symptoms, desilvering, rust, swelling and fog that never clears, are really humidity symptoms. If the bath fan is undersized, blocked or switched off the moment the shower ends, moisture sits on and inside the cabinet every single day. Canadian houses are sealed tight against winter from the Prairies to Quebec, so indoor humidity has nowhere to go, and the problem is worst in the cold months when warm shower air meets cool surfaces. Run the fan during the shower and for a good stretch afterward, and crack the door if the room has no fan at all. Replace the cabinet without fixing the ventilation and you have simply bought the same failure twice.
Recessed cabinets on exterior walls deserve special mention in a cold climate. The wall cavity behind them can run cold enough in a Manitoba or Quebec winter that the cabinet interior condenses moisture on its own, and cutting into an exterior wall raises insulation and vapour barrier questions that are building code territory and vary by province. If you are diagnosing a recessed unit that sweats every winter, the wall, not the cabinet, is the patient, and a local contractor should look before you order anything.
When replacement genuinely wins
Replacement is the right answer in a few clear situations:
- The carcass itself is compromised: swollen particleboard, rust-through, or laminate peeling in sheets. Once the structure is gone, repairs are wasted money.
- Desilvering has spread across the part of the mirror you actually use.
- The electrics are obsolete and the manufacturer no longer stocks drivers, strips or demister parts.
- You are renovating anyway and want what did not exist when your cabinet was installed: integrated LED lighting, demister pads, interior outlets for razors and toothbrushes, soft-close hinges and proper adjustable glass shelving.
If you land here, measure the old unit carefully before shopping, including the rough opening if it is recessed, and note whether wiring is already in the wall. Our medicine cabinet collection covers surface-mount and recessed models from brands like Sidler, Duravit and Kohler, with shipping available across Canada. For any hardwired lighted cabinet, look for recognized certification marks such as CSA on the electrical components and have an electrician handle the connection to satisfy your local code. And if the wall opening is damaged beyond easy repair, a surface-mount unit or a well-lit bathroom mirror paired with separate storage is often the cleaner path. For sizing and layout help, the rest of our bathroom and kitchen guides are worth a browse before you commit.
Frequently asked questions
Can I replace just the mirror or door on a medicine cabinet?
Often, yes. Many manufacturers sell doors, mirror panels, hinges and shelves as service parts for current and recent models. Check the brand and model before assuming the whole unit is done. On no-name builder-grade cabinets, parts support is rare, which quietly tilts the math toward replacement.
Why does my recessed medicine cabinet sweat or fog in winter?
If it sits in an exterior wall, the cavity behind it gets cold in a Canadian winter and warm bathroom air condenses on the chilled surfaces. Better ventilation helps, but the real issue is insulation behind the cabinet, and a new unit in the same opening will sweat too.
Do lighted medicine cabinets need an electrician in Canada?
Plug-in models just need a nearby outlet. Hardwired models should be connected by a licensed electrician under your provincial electrical code, and the cabinet's electrical components should carry a recognized certification mark such as CSA.
Is it worth repairing an old medicine cabinet?
Use the carcass as your test. If the box is sound, hinges, catches, clips and even LED drivers are cheap fixes worth doing. If the box is swollen, rusted or delaminating, or the mirror is failing across its face, put the repair money toward a replacement instead.
