Take sildenafil at around the same times every day. Check with your doctor immediately if any of the following side effects occur: Less common burning feeling in the chest or stomach burning, crawling, itching, numbness, prickling, “pins and needles”, or tingling feelings cloudy or bloody urine. If you experience chest pain, dizziness, or nausea during sexual activity, call your doctor immediately and avoid sexual activity until your doctor tells you otherwise. If you experience a sudden loss of vision in one or both eyes, contact your doctor immediately. If chest pains, dizziness, or nausea are experienced during sex, the exertion should be stopped and your doctor informed. New Zealand Sildenafil was reclassified in New Zealand in so it could be bought over the counter from a pharmacist. Storage Store the medicine in a closed container at room temperature, away from heat, moisture, and direct light.Is there an over-the-counter Viagra? Viagra is only available with a prescription in the United States, Canada, and most other countries. Viagra is sold . Oral medications, like Viagra and Cialis, which require a prescription and are commonly used to treat ED, can take 30 minutes to take effect, she adds. Injections take less time to work, but they. Examples of Viagra’s more commonly reported side effects include: headache. flushing (temporary warmth, redness, or deepening of skin color) stuffy nose. indigestion (upset stomach) mild vision.