Why isn't my listed dependent who is 15 not showing up in the Medical Expenses patient drop down?

First, make sure that you added your child as a dependent. To jump back to this step in your TurboTax return, select your product from the list provided:

For TurboTax Online: 

1. Select Find from the menu
2. In the Find window, enter dependants and select Go
3. Answer Yes to the question Do you have children or financially support another person?
4. Complete the Tell us about your dependant(s) section
5. Select Continue

For TurboTax CD/Download: 

1. Select Find from the menu and enter dependants
2. Select Dependants from the list, then select Go
3. If you've already entered one or more dependants, skip to Step 6. If not, answer Yes to the question Do you have children or financially support another person?, then select Continue
4. Select Continue on the dependant transfer step
5. Enter your dependant's information and select Continue
6. On the Dependants Summary, select Enter New Dependant or Done With Dependants, as applicable.

Once you have completed this step and/or confirmed that your child has been entered as a dependent, visit https://turbotax.community.intuit.ca/turbotax-support/en-ca/help-article/medical-tax-credits-deductions/enter-medical-expenses/L3eIlNS9Y_CA_en_CA?uid=lh50seva and follow the prompts to enter your medical expenses.