Getting a Dive Medical Certificate on Koh Tao
Why does a dive school ask for a medical certificate ?
Because diving does things to the body that no other recreational activity does, and a few common conditions behave very differently under pressure. Air spaces compress and expand, gas dissolves into tissue, and a problem that is manageable on land — a chest condition, an ear that does not clear, a tendency to lose consciousness — becomes a serious hazard underwater where you cannot simply stop and sit down.
The form is a screening tool, not a test of fitness. Most divers answer no to everything and never see a doctor at all. You are reading this because you answered yes to at least one question, which means the agency wants a clinician to look at that specific thing rather than guess.
What happens during the assessment ?
A consultation with a doctor, an examination, and a decision. There is no pool test, no treadmill and no endurance component.
What the doctor reviews
The conversation covers your medical history in the areas that matter for diving: respiratory, cardiac, neurological, ear and sinus, and any medication you take. Expect questions about asthma and how it is controlled, any history of fainting or seizures, ear surgery or perforations, diabetes and how it is managed, and any recent surgery or illness. Be specific about dates and treatments where you can.
What gets examined
An examination follows, focused on the systems relevant to pressure: chest and breathing, heart, blood pressure, ears and eardrums with a digital otoscope, sinuses, and a basic neurological check. The ear examination matters more than people expect, because a partly blocked ear or a healed perforation changes the advice significantly.
Which conditions usually need clearance ?
| Condition | Why it matters underwater | Usual outcome |
|---|---|---|
| Asthma | Air trapping on ascent; exertion and cold triggers | Often cleared if well controlled and stable |
| Recent ear surgery or perforation | Pressure changes across the eardrum | Depends on healing and the surgery involved |
| Epilepsy or seizures | Loss of consciousness underwater is fatal | Usually requires specialist assessment |
| Diabetes | Hypoglycaemia while diving | Often cleared with good control and a plan |
| Heart conditions | Exertion, cold water, immersion effects | Depends entirely on the condition |
| Recent surgery | Healing, pain, medication | Usually a delay rather than a refusal |
| Pregnancy | Diving is not advised | Diving deferred |
| Current cold or congestion | Cannot equalise; barotrauma risk | Short postponement until it clears |
The certificate is completed on the agency's own form, so bring whichever one your school gave you. Where a condition needs a specialist opinion or documentation from your own doctor before it can be signed off, you are told at the visit rather than after it.
What the certificate does and does not say
A signed certificate records that a doctor assessed you as fit to dive at that point in time, sometimes with conditions attached. It is not a guarantee of safety and it does not replace the judgement you make on the day. Someone cleared last week who now has a heavy cold is not fit to dive today, and no piece of paper changes that.
It also does not transfer responsibility. Dive schools still expect you to declare changes in your health, and insurers still expect the same. Treat the certificate as a snapshot rather than a permanent clearance, and say something if your circumstances change during the course.
Why honesty on the form is in your interest
Divers occasionally reason that ticking no to everything avoids the whole process. It is worth being blunt about why that is a bad trade. An undeclared condition does not disappear at ten metres — it simply means the person treating you does not know about it, and it may invalidate your insurance at exactly the moment you need it most.
The realistic outcome of declaring something is not refusal. Most conditions are cleared, some are cleared with conditions attached, and a few are postponed until something resolves. Outright refusal is uncommon and reserved for situations where the risk is genuinely unacceptable.
If you are refused or deferred
It happens rarely, and it is worth knowing what it actually means. A deferral is by far the more common outcome: a cold that needs to clear, a recent operation that needs more healing time, or a condition that needs documentation from your own doctor before a decision can be made. In most of those cases you dive later in the same trip.
A genuine refusal means the risk was judged unacceptable for that person diving at that time, and it is not a verdict delivered casually. Ask what specifically drove the decision and whether it is permanent or conditional, because some conditions can be reassessed after treatment or a specialist opinion.
What should you bring ?
- The form from your dive school, completed and signed by you.
- Your passport, for registration.
- Any medication you take, in its original packaging.
- Documentation from your own doctor where a condition is being managed — a letter or summary helps considerably.
- Details of any previous dive medical, including anything that was flagged.
- Your insurance policy, in case anything else comes up during the visit.
How do you avoid losing a day of your course ?
Come in the day before your course starts rather than the morning it does. Most assessments are completed in one visit, but where a specialist opinion or documentation from your home doctor is needed, that takes time you will not have if you turn up an hour before the theory session.
If you have a cold, congestion or an ear problem on the day, say so immediately. A short postponement while it clears is inconvenient; attempting to equalise through a blocked ear is how divers end up with barotrauma and a genuinely spoiled week. The practical detail on hours and costs is covered separately, and what happens if something goes wrong on a dive is worth reading before you get in the water rather than after.
For background on the medical standards themselves, Divers Alert Network publishes guidance on fitness to dive that is the standard reference in the recreational diving world.
Should you come in ?
- Your form has any yes on it → yes, bring it in
- You have a cold or blocked ear today → come in and say so before your course starts
- You take regular medication → yes, bring the packaging
- Your form is all no → usually no medical is needed; check with your school
- You have dived before with a cleared condition → bring the previous paperwork
- Course starts tomorrow and you have not done it → come in today
Frequently Asked Questions
How long does a dive medical take?
Usually a single visit. Allow extra time where a condition needs documentation from your own doctor or a specialist opinion, which is why coming in before your course starts matters.
Can I be refused a dive medical certificate?
It is uncommon. Most conditions are cleared, some with conditions attached, and a few are postponed until something resolves. Outright refusal is reserved for genuinely unacceptable risk.
Do I need a dive medical if my form is all no?
Usually not. The form itself is the screening step and most divers never need a doctor. Your dive school will tell you if a signed medical is required.
Can I dive with asthma?
Many people with well-controlled asthma are cleared to dive. It depends on how it is controlled, what triggers it and how recently you have had symptoms, which is exactly what the assessment establishes.
How long is a dive medical certificate valid?
Validity varies by agency and by any condition noted on it. Ask at the visit and keep a photograph of the certificate, since dive schools elsewhere will often accept it.
What if I have a cold on the day of my medical?
Say so. Congestion prevents equalising and makes barotrauma likely, so the usual advice is a short postponement rather than clearing you to dive through it.
Need help with diving medicine?
Dive-fitness checks, dive injury assessment and hyperbaric chamber treatment on Koh Tao, Koh Phangan and Koh Samui.
See Diving Medicine