Do not take other medicines unless they have been discussed with your doctor. Call your doctor right away if you have blurred vision, confusion, dizziness, faintness, or lightheadedness when getting up from a lying or sitting position suddenly, sweating, or unusual tiredness or weakness. Follow your doctor’s orders or the directions on the label. Mutagenesis Sildenafil was negative in in vitro bacterial and Chinese hamster ovary cell assays to detect mutagenicity, and in vitro human lymphocytes and in vivo mouse micronucleus assays to detect clastogenicity. How should this medicine be used? Tell your doctor if sildenafil is not working well or if you are experiencing side effects. This condition may require prompt medical treatment to prevent serious and permanent damage to your penis.Prescription drugs. Is it true i can buy prescription drugs over the counter in costa rica? drugs like hydrocodone and celebrex? Pharmacies in Costa Rica give extra discounts on every original box returned for certain opiates like Viagra or Lipitor. Some pills can also be bought separately in blisters instead . For these reason, the Costa Rican culture tends to self medicate and overuse pharmaceutical drugs. For example, at a farmacia and without a prescription you can get .