Drinking from pewter beer mugs is safe as long as it's not old pewter. Pewter made in the United States and England after the late 1700s is lead-free. However, older pewter may contain lead. Therefore, avoid drinking from mugs made of old pewter or pewter you can't verify.
Old vs. Modern Pewter
Old pewter is a metal alloy made up of about 90 per cent tin, which gives it a silvery sheen, and lead, which adds weight and strength. Modern pewter is also primarily tin-based, but rather than lead, the alloy is made up of a balance of antimony and copper.
Identifying Old Pewter
Check the bottoms of old pewter mugs to see if they were stamped by the maker. Stamps tend to include when the item was created and where. If there is a stamp and it was not made in the United States or England after 1700, assume it was made with lead.
If you have a beer mug made with old pewter that you believe has lead in it, don't drink from it and use it for ornamental purposes instead. Drinking from old pewter made with lead puts you at risk for lead poisoning because liquids filling the mug absorb the lead and get into your system.