How to use Valium. Read the Medication Guide provided by your pharmacist before you start taking diazepam and each time you get a refill. If you have any questions, ask your doctor or pharmacist. Get emergency medical help if you have signs of an allergic reaction to Valium: hives; difficult breathing; swelling of your face, lips, tongue, or throat. Diazepam can slow or stop your breathing, and death may occur. Old Valium loses potency, but doesn't go bad the way tetracyclines go bad. Old Valium won't hurt you, but 10 year-old 5 mg Valium will no longer be 5 mg of Valium. Depending on storage conditions (unopened/dark/cool/dry is best) that pill will contain only a percentage of its original potency. Diazepam (Valium®) has many uses in both dogs and cats and is a commonly used medication. Diazepam is effective as an anti-anxiety medication, a muscle relaxant, an appetite stimulant, and as a medication to control seizure activity. Valium is a brand name for the drug diazepam, and Xanax is a brand name for the drug alprazolam. Both of these drugs are minor tranquilizers. Both of these drugs are minor tranquilizers. Diazepam, first marketed as Valium, is a medicine of the benzodiazepine family that typically produces a calming effect. It is commonly used to treat a range of conditions including anxiety. If you had a prescription just get a fresh one. If you didn't then, well, I'd still flush them. Hope this helps. If you didn't then, well, I'd still flush them. Hope this helps. Best Answer: I suffer from generalized anxiety disorder and get panic attacks. This has been going on since I was 16 yrs old. I used to take valium but then was switched to xanax; which I am on now. Doctors give trusted answers on uses, effects, side-effects, and cautions: Dr. Pappas on does valium expire: Look on the bottle - there should be a date there. Doctors give trusted answers on uses, effects, side-effects, and cautions: Dr. Pappas on does valium expire: Look on the bottle - there should be a date there. Hey I have a bottle of Diazepam (Valium) from either '03 or '04 (i cant remember) Does the stuff expire? If it does, does it become harmful, or just less effective?.