Guidelines and Precautions. The jury is still out on melatoninâs effects on blood pressure. If you have high or low blood pressure, or take medications to control your blood pressure, it is best to avoid the supplement unless advised otherwise by your doctor.uidelines and Precautions. The jury is still out on melatoninâs effects on blood pressure. If you have high or low blood pressure, or take medications to control your blood pressure, it is best to avoid the supplement unless advised otherwise by your doctor.
1 This can cause the can to bulge or rust.  Use canned tuna by the expiration date on the can. If the can doesn't have a best by date, mark it with the date of purchase and use the tuna within 12 to 24 months of purchase.
Report Abuse. 1  I always make tuna fish salad, and it usually lasts for a week in the fridge. i mean that's how long i let it last b4 i eat it all up. lol it's still good. 2  I only keep it for one or two days after I make it, because the lettuce gets mushy and it develops a lot of liquid in the bottom of the bowl.