Most medications do not prevent you from donating blood. Common medications such as those used to control blood pressure, birth control pills and over-the-counter medications do not affect your eligibility. If you have recently taken antibiotics, you must have completed the course prior to donating.
Yes, a tooth infection can cause a headache. Also, be aware that certain sinus conditions can mask as tooth problems.
TMJ/TMD (Temporomandibular Joint Disorder), sinus or ear infections, and tension in the facial muscles can cause discomfort that resembles a toothache, but often these health problems are accompanied by a headache. Pain around the teeth and the jaws can be symptoms of heart disease such as angina.