1. en cuanto (tomar) el calmante, sentirás menos dolor.
2. la enfermera me va a poner una venda para que mi herida (curarse) más rápido.
3. a menos que (tener) fiebre, no puedo darte antibióticos.
4. después de que (ir) al dentista, te daré unos dulces.
5. no puedo saber si tienes un hueso roto hasta que el doctor te (hacer) una radiografía.
6. el cirujano va a operarlo siempre que (necesitar) una cirugía.

1. tomes

2. se cure

3. tengas

4. que vayas

5. haga

6. necesite

Explanation:

1. tomes . This is subjunctive first person conjugation, used often for the expression of unreality or supposition, therefore you must use "tomes".

2. se cure  This is the subjunctive third person present form of curarse, so we use"se cure"

3. tengas  This is the subjunctive second person, so we use "tengas"

4. vayas  This is the subjunctive second person of "ir", which is an irregular verb so it has a particular form of conjugation, "tengas" being the proper one for this sentence

5. haga  This is the subjunctive third person of "hacer", also an irregular verb, "haga" is the proper form

6. necesite This is the subjunctive third person of necesitar, so we use "necesite"

Subjunctive always expresses irreality, so it's used for hypotheticals or suppositions. The conjungations are a little trickier, specially for irregular verbs but you can always check them out online until you learn them all.